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

docs-site/troubleshooting.md

@@ -243,6 +243,8 @@ Subtitle tracks mpv loaded from a URL are downloaded to a temporary file first,
 
 Internal subtitle tracks of a stream still go through `ffmpeg`, which has to reach the origin itself. If that fails, prefer an external track or a Jimaku download as the reference.
 
+Streams usually serve WebVTT, which alass cannot parse — it picks its parser from the file extension and treats a `.vtt` file as a video, failing with "no audio stream in file". SubMiner rewrites both the target and the reference as SRT for alass, so this is handled automatically; the retimed track mpv loads is that SRT.
+
 ## TsukiHime
 
 **"xz binary not found"**