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

server/api/admin/schedule.post.ts

@@ -1,5 +1,13 @@
 import { db } from '~/drizzle/db'
-import { playTimes, schedules, songs, users, votes, songReplayRequests } from '~/drizzle/schema'
+import {
+  playTimes,
+  schedules,
+  songs,
+  users,
+  votes,
+  songReplayRequests,
+  scheduleSongPool
+} from '~/drizzle/schema'
 import { and, asc, count, desc, eq, gte, lte } from 'drizzle-orm'
 import { createSongSelectedNotification } from '../../services/notificationService'
 import { cacheService } from '~~/server/services/cacheService'
@@ -126,6 +134,19 @@ export default defineEventHandler(async (event) => {
       // 获取客户端IP地址
       const clientIP = getClientIP(event)
 
+      await tx
+        .update(scheduleSongPool)
+        .set({
+          status: 'ASSIGNED',
+          targetPlayDate: playDate
+        })
+        .where(
+          and(
+            eq(scheduleSongPool.songId, body.songId),
+            eq(scheduleSongPool.status, 'PENDING')
+          )
+        )
+
       // 只有在非草稿模式下才创建通知
       if (!isDraft) {
         await createSongSelectedNotification(