feat: 新增音乐播放模块

- 新增 Music 数据模型 + 迁移（title/subtitle/audioFile）
- 后端：公共 /api/music 查询接口 + 管理端 CRUD
  （音频上传专用 multer，限制 20MB）
- 移动端 /music/:id 播放页：
  - 金色印章式唱片 + 旋转虚线环 + 三重金色涟漪
  - preload=auto + HTTP Range 流式加载
  - 浏览器禁止 autoplay 时显示「轻点聆听」overlay
  - 自定义进度条与时间显示
- Admin：新增音乐管理三页（列表/表单/二维码）与侧栏入口
- 导入示例音乐：朝天宫之歌
- Dockerfile + entrypoint 增加 music 资产回灌

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker/entrypoint.sh

@@ -6,6 +6,7 @@ cd /app
 mkdir -p /app/data
 mkdir -p /app/packages/server/uploads/stamps
 mkdir -p /app/packages/server/uploads/articles
+mkdir -p /app/packages/server/uploads/music
 
 # Seed stamp assets on first run (idempotent)
 if [ -z "$(ls -A /app/packages/server/uploads/stamps 2>/dev/null)" ]; then
@@ -19,6 +20,12 @@ if [ -z "$(ls -A /app/packages/server/uploads/articles 2>/dev/null)" ]; then
   cp /app/articles-seed/*.jpg /app/packages/server/uploads/articles/ 2>/dev/null || true
 fi
 
+# Seed music assets on first run (idempotent)
+if [ -z "$(ls -A /app/packages/server/uploads/music 2>/dev/null)" ]; then
+  echo "→ Seeding music assets into uploads volume..."
+  cp /app/music-seed/* /app/packages/server/uploads/music/ 2>/dev/null || true
+fi
+
 echo "→ Applying database migrations..."
 pnpm exec prisma migrate deploy