fix(subsync): decode file:// tracks mpv reports for dropped subtitles

- Sync a subtitle dropped onto mpv without hitting "Protocol file: not supported"; decode file:// external-filename/path back to a real path for target, reference, and video
- Stream strip proxy: destroy the connection instead of retrying/502 once a response is handed off, and cap buffered playlist bodies
- Bridge installer: cap downloaded bundle size to guard against a lying/missing content-length
- Anime browser playback: bump generation on dispose so a stale in-flight playEpisode cleans up its own subtitle cache
- Fix a flaky sidecar-process test by binding to an OS-assigned port instead of pre-allocating one

src/main/runtime/anime-browser-playback.ts

@@ -183,6 +183,9 @@ export function createAnimeBrowserPlayback(options: AnimeBrowserPlaybackOptions)
   }
 
   async function dispose(): Promise<void> {
+    // Bumping the generation makes any in-flight playEpisode stale, so a cache
+    // it is still writing gets removed by that call instead of outliving us.
+    playbackGeneration += 1;
     const cacheDir = subtitleCacheDir;
     subtitleCacheDir = null;
     await removeSubtitleCache(cacheDir, deps.subtitleCacheIo);