feat(schedule)+fix(schedule)+feat(player): 排期管理5项功能 - 紧凑布局/投稿人优先算法/localStorage持久化/备选池修复/播放队列按钮

* fix+style(schedule): ScheduleManager 标签页紧凑布局，头部 min-height 防抖，内容区统间距与移动端适配
* feat(schedule): 新增自动排期策略「按投稿人数优先覆盖」，按 requester+collaborators 数排序分配好时段
* feat(schedule): localStorage 键 voicehub:schedule:auto-config 持久化策略/时段/学期/过滤等7项，onMounted 恢复，watch debounce 500ms 保存
* fix(schedule): songs/index.get.ts 新增 use_pool 查询参数，备选池过滤条件 status=PENDING + song.played=false + song未在任何排期中；ScheduleManager/draft-bulk 创建排期时将池记录 UPDATE 为 ASSIGNED
* feat(player): ScheduleManager 工具栏新增「构建播放队列」按钮，按 playDate+playTimeId+sequence 排序后调用 useAudioPlayer.playSong 加载播放列表，支持 confirm 确认与 toast 反馈
* refactor(useSongs): fetchSongs 增加第5参数 usePool，透传 use_pool=true 到 /api/songs

app/composables/useSongs.ts

@@ -75,7 +75,8 @@ export const useSongs = () => {
     silent = false,
     semester?: string,
     forceRefresh = false,
-    bypassCache = false
+    bypassCache = false,
+    usePool = false
   ) => {
     if (!silent) {
       loading.value = true
@@ -88,21 +89,21 @@ export const useSongs = () => {
       const response = await dedup.dedupedRequest(
           'songs',
           async () => {
-            // 构建URL参数
             const params = new URLSearchParams()
             if (semester) {
               params.append('semester', semester)
             }
-            // 只有当 bypassCache 为 true 时才添加 bypass_cache 参数
             if (bypassCache) {
               params.append('bypass_cache', 'true')
             }
+            if (usePool) {
+              params.append('use_pool', 'true')
+            }
             if (forceRefresh) {
               params.append('t', Date.now().toString())
             }
             const url = `/api/songs${params.toString() ? '?' + params.toString() : ''}`
 
-            // API请求
             return await $fetch(url, {
               ...getAuthConfig()
             })