v1.0.4

Fixes

• HLS playback on Windows: ffmpeg now receives forward-slash paths, fixing
  the 404 on fragment load that hit videos with soft subtitles or certain
  codec combinations (mkv, avi mpeg4/mp3).
• Native HLS support is now asked of the platform (WebKit) instead of the
  playback engine, avoiding a mismatch that could pick the wrong playback
  path.
• Pinned ffmpeg build repointed to a live BtbN release tag; the previous one
  had aged out of BtbN's history and broke CI/build fetches.