feat(ui): 设置页第一版（缓存管理 / 诊断导出 / 连接状态 / 关于）

设置页此前没有任何入口，且内容全是占位。现在：
- 首页右上角菜单按钮 → 设置页
- 缓存：标签条数、封面数量/占用、临时探测文件占用，一键清理（保留歌单与收藏）
- 诊断：导出 版本/连接/缓存/当前播放/最近错误 到 txt，经 FileProvider 走系统分享
- 连接：显示 WebDAV 地址与用户，支持测试连接、退出登录
- 关于：版本、构建号、播放内核与 UI 许可说明
- 删除未被引用的 FullPlayerPage（与 player_page 重复）

真机验证：设置页正常打开，诊断导出成功调起系统分享面板。

lib/pages/settings_page.dart

@@ -1,59 +1,367 @@
-import 'package:flutter/material.dart';
+// lib/pages/settings_page.dart
+import 'dart:io';
 
-class SettingsPage extends StatelessWidget {
+import 'package:android_intent_plus/android_intent.dart';
+import 'package:android_intent_plus/flag.dart';
+import 'package:flutter/material.dart';
+import 'package:path_provider/path_provider.dart';
+
+import '../database/song_database.dart';
+import '../services/audio_service.dart';
+import '../services/webdav_service.dart';
+import '../utils/file_provider_utils.dart';
+
+/// 与 pubspec.yaml 的 version 保持同步（发版时一起改）
+const String kAppVersion = '1.1.0-dev.1';
+const int kAppBuild = 2;
+
+class SettingsPage extends StatefulWidget {
   const SettingsPage({super.key});
 
   @override
-  Widget build(BuildContext context) {
-    return Scaffold(
-      appBar: AppBar(title: const Text('设置')),
-      body: ListView(
-        children: [
-          const SizedBox(height: 20),
-          _buildTile(
-            icon: Icons.folder_open_outlined,
-            title: '本地文件 (SAF)',
-            subtitle: '通过系统文件选择器导入',
-            onTap: () {
-              // 🟢 这里粘贴你旧项目的 SAF 逻辑
-              ScaffoldMessenger.of(context).showSnackBar(
-                const SnackBar(content: Text('待接入 SAF 逻辑')),
-              );
-            },
+  State<SettingsPage> createState() => _SettingsPageState();
+}
+
+class _SettingsPageState extends State<SettingsPage> {
+  bool _loading = true;
+
+  int _songRows = 0;
+  int _metadataRows = 0;
+  int _favoriteRows = 0;
+  int _artworkCount = 0;
+  int _artworkBytes = 0;
+  int _tempCount = 0;
+  int _tempBytes = 0;
+
+  @override
+  void initState() {
+    super.initState();
+    _loadStats();
+  }
+
+  Future<void> _loadStats() async {
+    setState(() => _loading = true);
+    try {
+      final db = await SongDatabase().database;
+      final songRows =
+          (await db.rawQuery('SELECT COUNT(*) AS c FROM songs')).first['c'];
+      final metaRows = (await db.rawQuery(
+              'SELECT COUNT(*) AS c FROM metadata_cache'))
+          .first['c'];
+      final favRows =
+          (await db.rawQuery('SELECT COUNT(*) AS c FROM favorites')).first['c'];
+
+      var artworkCount = 0, artworkBytes = 0;
+      final docs = await getApplicationDocumentsDirectory();
+      final artDir = Directory('${docs.path}/artworks');
+      if (await artDir.exists()) {
+        await for (final entity in artDir.list()) {
+          if (entity is File) {
+            artworkCount++;
+            artworkBytes += await entity.length();
+          }
+        }
+      }
+
+      var tempCount = 0, tempBytes = 0;
+      final tmp = await getTemporaryDirectory();
+      if (await tmp.exists()) {
+        await for (final entity in tmp.list()) {
+          if (entity is File &&
+              entity.path.contains('/metadata_') &&
+              entity.path.endsWith('.part')) {
+            tempCount++;
+            tempBytes += await entity.length();
+          }
+        }
+      }
+
+      if (!mounted) return;
+      setState(() {
+        _songRows = songRows as int? ?? 0;
+        _metadataRows = metaRows as int? ?? 0;
+        _favoriteRows = favRows as int? ?? 0;
+        _artworkCount = artworkCount;
+        _artworkBytes = artworkBytes;
+        _tempCount = tempCount;
+        _tempBytes = tempBytes;
+        _loading = false;
+      });
+    } catch (e) {
+      debugPrint('⚠️ [Settings] 统计失败: $e');
+      if (mounted) setState(() => _loading = false);
+    }
+  }
+
+  Future<void> _clearMetadataCache() async {
+    final confirmed = await showDialog<bool>(
+      context: context,
+      builder: (context) => AlertDialog(
+        backgroundColor: const Color(0xFF1A1F1E),
+        title: const Text('清理元数据缓存', style: TextStyle(color: Colors.white)),
+        content: const Text(
+          '会删除歌曲标签缓存和封面文件，歌单与收藏不受影响。\n下次播放时重新抓取。',
+          style: TextStyle(color: Colors.grey),
+        ),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(context, false),
+            child: const Text('取消'),
           ),
-          _buildTile(
-            icon: Icons.cloud_outlined,
-            title: 'WebDAV 云盘',
-            subtitle: '连接你的 NAS 或网盘',
-            onTap: () {
-              // 🟢 这里调用你现成的 WebDAV 通道
-              ScaffoldMessenger.of(context).showSnackBar(
-                const SnackBar(content: Text('待接入 WebDAV 逻辑')),
-              );
-            },
-          ),
-          _buildTile(
-            icon: Icons.equalizer_outlined,
-            title: '均衡器',
-            subtitle: '简单低音增强 (后续)',
-            onTap: () {},
+          TextButton(
+            onPressed: () => Navigator.pop(context, true),
+            child: const Text('清理', style: TextStyle(color: Colors.redAccent)),
           ),
         ],
       ),
     );
+    if (confirmed != true) return;
+
+    try {
+      final db = await SongDatabase().database;
+      await db.delete('songs');
+      await db.delete('metadata_cache');
+
+      final docs = await getApplicationDocumentsDirectory();
+      final artDir = Directory('${docs.path}/artworks');
+      if (await artDir.exists()) {
+        await artDir.delete(recursive: true);
+      }
+
+      final tmp = await getTemporaryDirectory();
+      if (await tmp.exists()) {
+        await for (final entity in tmp.list()) {
+          if (entity is File &&
+              entity.path.contains('/metadata_') &&
+              entity.path.endsWith('.part')) {
+            await entity.delete();
+          }
+        }
+      }
+
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('元数据缓存已清理')),
+        );
+      }
+      await _loadStats();
+    } catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context)
+            .showSnackBar(SnackBar(content: Text('清理失败: $e')));
+      }
+    }
+  }
+
+  Future<void> _exportDiagnostics() async {
+    try {
+      final now = DateTime.now();
+      final docs = await getApplicationDocumentsDirectory();
+      final file =
+          File('${docs.path}/diagnostics-${now.millisecondsSinceEpoch}.txt');
+
+      final song = AudioService().currentSong;
+      final buffer = StringBuffer()
+        ..writeln('清听 诊断信息')
+        ..writeln('时间: ${now.toIso8601String()}')
+        ..writeln('版本: $kAppVersion ($kAppBuild)')
+        ..writeln('平台: ${Platform.operatingSystem} ${Platform.operatingSystemVersion}')
+        ..writeln()
+        ..writeln('[连接]')
+        ..writeln('baseUrl: ${WebDAVService.instance.baseUrl ?? '(未配置)'}')
+        ..writeln('username: ${WebDAVService.instance.username ?? '(未配置)'}')
+        ..writeln('connected: ${WebDAVService.instance.isConnected}')
+        ..writeln()
+        ..writeln('[数据]')
+        ..writeln('songs: $_songRows')
+        ..writeln('metadata_cache: $_metadataRows')
+        ..writeln('favorites: $_favoriteRows')
+        ..writeln('artwork 文件: $_artworkCount 个 / ${_formatBytes(_artworkBytes)}')
+        ..writeln('临时探测文件: $_tempCount 个 / ${_formatBytes(_tempBytes)}')
+        ..writeln()
+        ..writeln('[当前播放]')
+        ..writeln('song: ${song?.title ?? '(无)'} - ${song?.artist ?? ''}')
+        ..writeln('path: ${song?.id ?? ''}')
+        ..writeln('position: ${AudioService().position}')
+        ..writeln('duration: ${AudioService().duration}')
+        ..writeln('lastError: ${AudioService().lastPlaybackError ?? '(无)'}');
+
+      await file.writeAsString(buffer.toString());
+      if (!mounted) return;
+
+      final uri = await FileProviderUtils.getContentUri(file);
+      if (uri != null) {
+        try {
+          final intent = AndroidIntent(
+            action: 'android.intent.action.SEND',
+            type: 'text/plain',
+            arguments: {
+              'android.intent.extra.STREAM': uri.toString(),
+              'android.intent.extra.SUBJECT': '清听诊断信息',
+            },
+            flags: const [Flag.FLAG_GRANT_READ_URI_PERMISSION],
+          );
+          await intent.launch();
+          return;
+        } catch (e) {
+          debugPrint('⚠️ [Settings] 分享失败: $e');
+        }
+      }
+
+      if (mounted) {
+        showDialog<void>(
+          context: context,
+          builder: (context) => AlertDialog(
+            backgroundColor: const Color(0xFF1A1F1E),
+            title: const Text('诊断信息已导出', style: TextStyle(color: Colors.white)),
+            content: SelectableText(
+              file.path,
+              style: const TextStyle(color: Colors.grey, fontSize: 12),
+            ),
+            actions: [
+              TextButton(
+                onPressed: () => Navigator.pop(context),
+                child: const Text('好'),
+              ),
+            ],
+          ),
+        );
+      }
+    } catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context)
+            .showSnackBar(SnackBar(content: Text('导出失败: $e')));
+      }
+    }
+  }
+
+  Future<void> _testConnection() async {
+    try {
+      await WebDAVService.instance.listDirectory(path: '/');
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('连接正常')),
+        );
+      }
+    } catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text('连接失败: $e')),
+        );
+      }
+    }
+  }
+
+  Future<void> _logout() async {
+    await WebDAVService.instance.clearCredentials();
+    if (mounted) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('已退出登录，下次进入会要求重新配置')),
+      );
+    }
+  }
+
+  String _formatBytes(int bytes) {
+    if (bytes < 1024) return '$bytes B';
+    if (bytes < 1024 * 1024) return '${(bytes / 1024).toStringAsFixed(1)} KB';
+    return '${(bytes / 1024 / 1024).toStringAsFixed(1)} MB';
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      backgroundColor: const Color(0xFF0E1211),
+      appBar: AppBar(
+        backgroundColor: Colors.transparent,
+        elevation: 0,
+        title: const Text('设置'),
+      ),
+      body: _loading
+          ? const Center(child: CircularProgressIndicator())
+          : ListView(
+              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+              children: [
+                _sectionTitle('缓存'),
+                ListTile(
+                  leading: const Icon(Icons.cleaning_services_outlined,
+                      color: Color(0xFF7C9A9E)),
+                  title: const Text('元数据缓存'),
+                  subtitle: Text(
+                    '标签 $_songRows 首 · 封面 $_artworkCount 张 '
+                    '(${_formatBytes(_artworkBytes)}) · 临时文件 ${_formatBytes(_tempBytes)}',
+                    style: const TextStyle(fontSize: 12),
+                  ),
+                  trailing: const Icon(Icons.chevron_right, color: Colors.grey),
+                  onTap: _clearMetadataCache,
+                ),
+                _sectionTitle('诊断'),
+                ListTile(
+                  leading: const Icon(Icons.bug_report_outlined,
+                      color: Color(0xFF7C9A9E)),
+                  title: const Text('导出诊断信息'),
+                  subtitle: const Text(
+                    '版本、连接状态、缓存统计、当前播放与最近错误',
+                    style: TextStyle(fontSize: 12),
+                  ),
+                  trailing: const Icon(Icons.ios_share, color: Colors.grey),
+                  onTap: _exportDiagnostics,
+                ),
+                _sectionTitle('连接'),
+                ListTile(
+                  leading: const Icon(Icons.cloud_outlined,
+                      color: Color(0xFF7C9A9E)),
+                  title: Text(WebDAVService.instance.baseUrl ?? '(未配置)'),
+                  subtitle: Text(
+                    '用户 ${WebDAVService.instance.username ?? '-'} · '
+                    '${WebDAVService.instance.isConnected ? '已连接' : '未连接'}',
+                    style: const TextStyle(fontSize: 12),
+                  ),
+                ),
+                ListTile(
+                  leading: const Icon(Icons.wifi_tethering,
+                      color: Color(0xFF7C9A9E)),
+                  title: const Text('测试连接'),
+                  onTap: _testConnection,
+                ),
+                ListTile(
+                  leading:
+                      const Icon(Icons.logout, color: Colors.redAccent),
+                  title: const Text('退出登录'),
+                  subtitle: const Text(
+                    '清除本机保存的 WebDAV 账号',
+                    style: TextStyle(fontSize: 12),
+                  ),
+                  onTap: _logout,
+                ),
+                _sectionTitle('关于'),
+                ListTile(
+                  leading:
+                      const Icon(Icons.info_outline, color: Color(0xFF7C9A9E)),
+                  title: const Text('清听'),
+                  subtitle: const Text(
+                    '版本 $kAppVersion ($kAppBuild)\n'
+                    '播放内核 media_kit (libmpv, LGPL/GPL) · UI Flutter (BSD)',
+                    style: TextStyle(fontSize: 12),
+                  ),
+                ),
+                const SizedBox(height: 24),
+              ],
+            ),
+    );
+  }
+
+  Widget _sectionTitle(String text) {
+    return Padding(
+      padding: const EdgeInsets.fromLTRB(4, 20, 4, 8),
+      child: Text(
+        text,
+        style: const TextStyle(
+          fontSize: 13,
+          fontWeight: FontWeight.w600,
+          color: Color(0xFFB8D4D0),
+          letterSpacing: 1.2,
+        ),
+      ),
+    );
   }
 }
-
-Widget _buildTile(
-    {required IconData icon,
-    required String title,
-    required String subtitle,
-    required VoidCallback onTap}) {
-  return ListTile(
-    leading: Icon(icon, color: const Color(0xFF7C9A9E)),
-    title: Text(title),
-    subtitle: Text(subtitle, style: const TextStyle(fontSize: 12)),
-    trailing: const Icon(Icons.chevron_right, color: Colors.grey),
-    onTap: onTap,
-  );
-}