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/renderer/modals/tsukihime.test.ts

@@ -188,6 +188,7 @@ function createModalHarness(
         setAttribute: () => {},
       },
       tsukihimeTitleInput: { value: '' },
+      tsukihimeSeasonInput: { value: '' },
       tsukihimeEpisodeInput: { value: '' },
       tsukihimeSearchButton: { addEventListener: () => {} },
       tsukihimeCloseButton: { addEventListener: () => {} },