Fix subtitle timing, and AI subtitles

Timing fixer: Reelhost finds subtitles that run early or late and lines them up with the video. You see a preview first, and Undo puts the old timing back. Checking is free; fixing needs Complete or Yearly.

AI subtitles (Beta): free subtitles for any movie, made on your computer by the open-source Whisper model. No accounts, no limits, and nothing is sent anywhere. Reelhost checks your hardware first and works only while the computer is idle. It runs on Windows, on a Mac (Apple silicon uses its graphics) and in Docker, and needs Complete or Yearly. AI subtitles are new: accuracy depends on the audio, so check a few before relying on them.