fix(anime): scope preferences, paginate sources, harden installs

- Preference store keys entries by extension package + bridge source id; legacy unscoped entries are discarded once instead of being handed to whichever extension asks first
- Source picker's "Load more" appends the next page without duplicating streamed results
- Repository index fetches and subtitle/APK downloads now time out and are size-bounded instead of hanging or growing unbounded
- APK installs are staged to a temp file and renamed into place
- Stream metadata lookup matches the requested path, not only the currently playing one
- Reworked animeui into browse-state/detail-panel/panels.css modules
- Reverted premature CHANGELOG unreleased entries; refreshed anime-browser docs

src/core/services/subsync-extract.ts

@@ -100,6 +100,7 @@ async function extractInternalTrack(input: SubtitleExtractionInput): Promise<Fil
   if (!extension) {
     throw new Error(`Unsupported subtitle codec: ${input.track.codec ?? 'unknown'}`);
   }
+  const ffmpegMuxer = extension === 'vtt' ? 'webvtt' : extension;
 
   const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'subminer-subsync-'));
   try {
@@ -123,7 +124,7 @@ async function extractInternalTrack(input: SubtitleExtractionInput): Promise<Fil
       '-map',
       `0:${ffIndex}`,
       '-f',
-      extension,
+      ffmpegMuxer,
       outputPath,
     ]);