refactor(api)!: 平台 id 回退——joox/5sing/bili/apple 恢复全名，目录对齐 bd/mg

- 撤销 3381e9b/1b972ec 中 jx/5s/bl/ap 四个短码，恢复 joox/5sing/bili/apple；
  qian→bd、migu→mg 保留
- 目录与文件对齐保留的新 id：sdk/qian/→sdk/bd/、sdk/migu/→sdk/mg/、
  sdk/apis/qian.ts→bd.ts、migu.ts→mg.ts、src/http/migu-stream.ts→mg-stream.ts
  （规则改为「目录=对外 id」，聚合入口的模块变量同步更名；music.migu.cn 等域名、
  上游 music-lib 对照注释、miguGet 等功能标识符不动）
- 对外 id 全表：kw kg tx wy qs xm me qt lr mg bd joox 5sing bili apple

**破坏性变更**：joox/5sing/bili/apple 四平台的 URL、/sources 返回与
data/auth.json 凭据键恢复全名，已存短码键的登录态需重新登录。

验证：typecheck ✓、pnpm test 112/112 ✓

sdk/bili/playlist.ts

@@ -57,7 +57,7 @@ export const searchPlaylist = async(keyword: string, page = 1, limit = 20) => {
         creator: view?.owner?.name || item.author || '',
         description: season.intro || '',
         link: `https://www.bilibili.com/video/${item.bvid}`,
-        source: 'bl' as const,
+        source: 'bili' as const,
       }
     }
     const pages: any[] = view?.pages ?? []
@@ -73,14 +73,14 @@ export const searchPlaylist = async(keyword: string, page = 1, limit = 20) => {
         creator: view?.owner?.name || item.author || '',
         description: '',
         link: `https://www.bilibili.com/video/${item.bvid}`,
-        source: 'bl' as const,
+        source: 'bili' as const,
       }
     }
     return null
   })
 
   const list = result.filter(Boolean)
-  return { list, page: p, limit: l, total: list.length, source: 'bl' as const }
+  return { list, page: p, limit: l, total: list.length, source: 'bili' as const }
 }
 
 /** 由 bvid 构造歌单详情（上游 GetPlaylistSongs 的 bvid 分支 + ParsePlaylist 的元数据） */
@@ -167,7 +167,7 @@ const pageSlice = (detail: { info: any, songs: any[] }, page: any, limit: any) =
   const p = Math.max(1, Number(page) || 1)
   const l = Math.min(Math.max(1, Number(limit) || 100), 10000)
   return {
-    source: 'bl' as const,
+    source: 'bili' as const,
     info: detail.info,
     list: detail.songs.slice((p - 1) * l, p * l),
     page: p,
@@ -216,7 +216,7 @@ const parsePlaylistView = async(bvid: string, view: any) => {
     let trackCount = countSeasonEpisodes(season.sections)
     if (!trackCount) trackCount = detail.songs.length
     return {
-      source: 'bl' as const,
+      source: 'bili' as const,
       id,
       info: { ...detail.info, trackCount, playCount: Number(season?.stat?.view) || undefined },
       list: detail.songs,
@@ -227,7 +227,7 @@ const parsePlaylistView = async(bvid: string, view: any) => {
   }
   const detail = await detailFromBvid(bvid)
   return {
-    source: 'bl' as const,
+    source: 'bili' as const,
     id: bvidKey(bvid),
     info: { ...detail.info, trackCount: detail.songs.length },
     list: detail.songs,