fix(anime): thread episode metadata through stream playback and fix seas

- Split anime browser stream titles into series/season/episode fields (episode-metadata.ts) instead of one joined string, so stats grouping, the mpv title, and the Jimaku/TsukiHime modals all get real values instead of a filename-derived "m3u8"
- Fix AniList season resolver to walk through split-cour sequels and specials without counting them as a season, and to surface rate-limit/network failures instead of falling through to a wrong air-order guess
- Add a Season field to the TsukiHime modal and include later seasons in its search query
- Rewrite WebVTT subtitle tracks as SRT before handing them to alass, since alass has no VTT support and streams serve VTT
- Update CHANGELOG and troubleshooting docs

src/types/anime-browser.ts

@@ -166,6 +166,11 @@ export interface AnimeBrowserPlayRequest {
   animeTitle: string;
   episodeUrl: string;
   episodeName: string;
+  /**
+   * The episode's number as the source reported it. Carried rather than
+   * re-parsed out of `episodeName`, which is free-form and often lacks one.
+   */
+  episodeNumber: number | null;
 }
 
 export interface AnimeBrowserPlayResult {