perf: 优化专辑封面图片尺寸

- 在 MediaSessionManager 中将专辑封面图片尺寸从 512 调整为 300
- 在 musicPicCache 中强制使用 300 尺寸，忽略传入的 size 参数
- 这些更改可以减少图片加载时间，提高应用性能

src/utils/mediaSession.js

@@ -82,7 +82,7 @@ class MediaSessionManager {
       try {
         const { usePlayerStore } = await import('@/stores/player')
         const playerStore = usePlayerStore()
-        coverUrl = await playerStore.getAlbumCover(song, 512)
+        coverUrl = await playerStore.getAlbumCover(song, 300)
       } catch (error) {
         console.warn('获取专辑封面失败:', error)
       }

src/utils/musicPicCache.js

@@ -14,7 +14,8 @@ const pendingRequests = new Map()
 export async function getCachedMusicPicUrl(source, id, size = 300, skipCache = false) {
   if (!source || !id) return null
   
-  const sizeStr = String(size)
+  // 强制使用 300 尺寸，不管传入什么参数
+  const sizeStr = '300'
   
   // 先检查缓存（除非明确跳过）
   if (!skipCache) {
@@ -75,7 +76,8 @@ export async function getCachedMusicPicUrl(source, id, size = 300, skipCache = f
 export async function getCachedMusicPicUrlWithDelay(source, id, size = 300) {
   if (!source || !id) return null
   
-  const sizeStr = String(size)
+  // 强制使用 300 尺寸，不管传入什么参数
+  const sizeStr = '300'
   
   // 先检查缓存
   const cached = urlCacheManager.getCachedUrl(source, id, sizeStr)
@@ -91,7 +93,7 @@ export async function getCachedMusicPicUrlWithDelay(source, id, size = 300) {
     await new Promise(resolve => setTimeout(resolve, 200))
   }
   
-  return getCachedMusicPicUrl(source, id, size)
+  return getCachedMusicPicUrl(source, id, 300)
 }
 
 /**
@@ -103,7 +105,8 @@ export async function getCachedMusicPicUrlWithDelay(source, id, size = 300) {
 export async function preloadMusicPics(songs, size = 300, concurrency = 1) {
   if (!Array.isArray(songs) || songs.length === 0) return
   
-  const sizeStr = String(size)
+  // 强制使用 300 尺寸，不管传入什么参数
+  const sizeStr = '300'
   
   // 过滤出需要加载的歌曲（未缓存的）
   const toLoad = songs.filter(song => {
@@ -117,7 +120,7 @@ export async function preloadMusicPics(songs, size = 300, concurrency = 1) {
   for (let i = 0; i < toLoad.length; i += concurrency) {
     const batch = toLoad.slice(i, i + concurrency)
     const promises = batch.map(song => 
-      getCachedMusicPicUrl(song.source, song.pic_id, size).catch(error => {
+      getCachedMusicPicUrl(song.source, song.pic_id, 300).catch(error => {
         console.warn(`预加载 ${song.name} 图片失败:`, error)
         return null
       })