style(ui): 播放页内容下移 + 收藏移到标题右侧 + 底部改播放模式

按草图调整：
- 主播放页顶部留 16px，封面与指示器拉开距离
- 收藏心从底部控制行移到标题右侧（空心/实心红随收藏状态）
- 底部控制行第四位改为播放模式按钮（循环图标），队列保持在第五位

lib/pages/player_page.dart

@@ -307,7 +307,8 @@ class _PlayerPageState extends BaseState<PlayerPage> {
 
   Widget _buildMainPage(AudioService service, Song song, bool isPlaying) {
     return Padding(
-      padding: const EdgeInsets.symmetric(horizontal: 24),
+      // 顶部留 16：与 AppBar/指示器拉开距离，避免封面贴着顶部
+      padding: const EdgeInsets.fromLTRB(24, 16, 24, 0),
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.start,
         children: [
@@ -334,19 +335,38 @@ class _PlayerPageState extends BaseState<PlayerPage> {
           ),
           const SizedBox(height: 28),
 
-          // ---- 标题 / 艺术家 ----
-          Text(
-            song.title,
-            style: const TextStyle(
-              fontSize: 24,
-              fontWeight: FontWeight.w600,
-              color: Colors.white,
-              height: 1.25,
-            ),
-            maxLines: 2,
-            overflow: TextOverflow.ellipsis,
+          // ---- 标题 / 艺术家（收藏心在标题右侧）----
+          Row(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Expanded(
+                child: Text(
+                  song.title,
+                  style: const TextStyle(
+                    fontSize: 24,
+                    fontWeight: FontWeight.w600,
+                    color: Colors.white,
+                    height: 1.25,
+                  ),
+                  maxLines: 2,
+                  overflow: TextOverflow.ellipsis,
+                ),
+              ),
+              const SizedBox(width: 8),
+              IconButton(
+                onPressed: () => _toggleFavorite(song),
+                tooltip: '收藏',
+                icon: Icon(
+                  _isFavorite ? Icons.favorite : Icons.favorite_border,
+                  color: _isFavorite
+                      ? const Color(0xFFE05C5C)
+                      : Colors.white54,
+                  size: 26,
+                ),
+              ),
+            ],
           ),
-          const SizedBox(height: 6),
+          const SizedBox(height: 2),
           Text(
             song.artist,
             style: TextStyle(fontSize: 14, color: Colors.grey[400]),
@@ -641,15 +661,13 @@ class _PlayerPageState extends BaseState<PlayerPage> {
           color: service.hasQueue ? Colors.white70 : Colors.grey[700],
         ),
         IconButton(
-          onPressed: () => _toggleFavorite(song),
+          onPressed: service.togglePlayMode,
           icon: Icon(
-            _isFavorite ? Icons.favorite : Icons.favorite_border,
-            color: _isFavorite
-                ? const Color(0xFFE05C5C)
-                : Colors.white54,
+            service.playModeIcon,
+            color: const Color(0xFFB8D4D0),
             size: 26,
           ),
-          tooltip: '收藏',
+          tooltip: '播放模式',
         ),
         IconButton(
           onPressed: _openPlaylist,