4.12.1

Patch release.

Fixed

• mov_text subtitle OOM on the host overlay (#104 follow-up). 4.12.0 added the video/audio discard to the native PiP/AirPlay subtitle rendition reader only. The tvOS host-overlay reader is a separate side demuxer and still lacked the discard, so selecting an embedded text subtitle pulled the whole video and audio through a second connection just to reach the sparse subtitle samples, with RSS climbing by playback position until jetsam (worst on files carrying many subtitle tracks). The overlay side demuxer now sets AVDISCARD_ALL on everything except the selected subtitle stream, so mov_read_packet skips the video/audio byte reads and the reader fast-walks the in-memory index between cues. Adds a regression test that drives a real h264 + mov_text MP4 through the demuxer and asserts only subtitle packets are returned after the discard.

Full diff: 4.12.0...4.12.1