metadata读取能力已达成，接下来会顺着路径完成部分缓存指针设计

lib/metadata/metadata_normalizer.dart

@@ -4,20 +4,19 @@ import 'metadata_model.dart';
 class MetadataNormalizer {
   NormalizedMetadata normalize(RawMetadata raw,
       {String fileName = '', String filePath = ''}) {
-    // 1. 修剪空格
+    // 1. 修剪
     final title = raw.title.trim();
     final artist = raw.artist.trim();
-    final album = raw.album.trim();
 
     // 2. 如果 title 为空，从文件名推断
     final finalTitle =
         title.isNotEmpty ? title : _inferTitleFromFileName(fileName);
 
-    // 3. 如果 artist 为空，从路径推断或使用默认值
+    // 3. 如果 artist 为空，从路径推断
     final finalArtist =
         artist.isNotEmpty ? artist : _inferArtistFromPath(filePath);
 
-    // 4. 如果 performers 不为空且 artist 为空，用 performers 的第一个
+    // 4. 如果 performers 不为空且 artist 为空，使用 performers
     final finalArtist2 = finalArtist.isNotEmpty
         ? finalArtist
         : (raw.performers.isNotEmpty ? raw.performers.first : '未知艺术家');
@@ -25,7 +24,7 @@ class MetadataNormalizer {
     return NormalizedMetadata(
       title: finalTitle,
       artist: finalArtist2,
-      album: album,
+      album: raw.album,
       genres: raw.genres,
       performers: raw.performers,
       year: raw.year,
@@ -40,17 +39,16 @@ class MetadataNormalizer {
 
   String _inferTitleFromFileName(String fileName) {
     final dotIndex = fileName.lastIndexOf('.');
-    if (dotIndex > 0) {
-      return fileName.substring(0, dotIndex).trim();
-    }
-    return fileName.trim();
+    return dotIndex > 0
+        ? fileName.substring(0, dotIndex).trim()
+        : fileName.trim();
   }
 
   String _inferArtistFromPath(String filePath) {
     final parts = filePath.split(RegExp(r'[/\\]'));
     if (parts.length >= 2) {
       final candidate = parts[parts.length - 2].trim();
-      if (candidate.isNotEmpty && !candidate.contains(' ')) {
+      if (candidate.isNotEmpty && !candidate.startsWith('http')) {
         return candidate;
       }
     }