修复(服务器)：增强文件名清理的健壮性

实施更严格的文件名清理措施，包括Unicode标准化处理（NFC）、控制字符移除以及200字符的长度限制，以防止歌曲下载过程中出现文件系统错误。

sync-server/server.js

@@ -127,9 +127,20 @@ async function tryDownloadSongs(data) {
 
 function processSong(song) {
     return new Promise((resolve) => {
-        // Basic sanitization
-        const safeName = (song.name || 'unknown').replace(/[\\/:*?"<>|]/g, '_');
-        const safeArtist = (song.artist || 'unknown').replace(/[\\/:*?"<>|]/g, '_');
+        // Sanitize filename with proper encoding handling
+        const sanitizeFilename = (str) => {
+            if (!str) return 'unknown';
+            // Normalize Unicode (NFC) to ensure consistent encoding
+            const normalized = str.normalize('NFC');
+            // Replace Windows illegal characters and control characters
+            return normalized
+                .replace(/[\\/:*?"<>|\x00-\x1f\x7f]/g, '_')
+                .trim()
+                .substring(0, 200); // Limit length to avoid path too long errors
+        };
+
+        const safeName = sanitizeFilename(song.name);
+        const safeArtist = sanitizeFilename(song.artist);
         const source = song.platform || song.source;
         // Filename: Artist - Name [source_id]
         const baseName = `${safeArtist} - ${safeName} [${source}_${song.id}]`;