feat(subtitles): connect M-Team search and download to online workflow

通过既有provider表复用M-Team站点适配器的凭据、UA和共享限流；搜索只返回稳定字幕ID，下载签名现场获取，沿用沙箱解析、写入历史与撤销。迁移0096扩展字幕来源，schema反射同步。独立测试库验证M-Team真实API形状与旧字幕来源。参考：MoviePilot v3.2.4 app/modules/indexer/spider/mtorrent.py。

packages/contracts/src/subtitles.ts

@@ -17,7 +17,7 @@ export const SubtitleLanguage = z.enum([
 ]);
 export type SubtitleLanguage = z.infer<typeof SubtitleLanguage>;
 export const SubtitleExt = z.enum(["srt", "ass", "ssa", "vtt", "sub", "sbv"]);
-export const SubtitleSource = z.enum(["upload", "subhd", "zimuku"]);
+export const SubtitleSource = z.enum(["upload", "subhd", "zimuku", "mteam"]);
 export type SubtitleSource = z.infer<typeof SubtitleSource>;
 
 /** 可写字幕的视频(作品在媒体库里的视频位置) */
@@ -146,7 +146,7 @@ export const SubtitleWriteRow = z.object({
 export const SubtitleWritesQuery = z.object({ entityId: Id });
 export const SubtitleWritesResponse = z.object({ items: z.array(SubtitleWriteView) });
 
-// ── 在线(字幕站:SubHD、字幕库) ──
+// ── 在线(字幕站:SubHD、字幕库；已启用的 M-Team 站点) ──
 
 export const SubtitleSearchRequest = z.object({
   entityId: Id,