tapes: theatre-mode playback UI + bigger video preview
When a tape is loaded, the browser transforms into a cinema-style
player: the video fills most of the screen (largest 16:9 rect that
fits), wrapped in a black letterbox background with a film-border
frame. The title + progress bar + time labels sit in a chrome band
at the bottom; list view is hidden while playback is active.
Controls in theatre mode:
- Space / Enter: pause / resume
- Escape: stop + unload (returns to list)
- Escape again (from list): exit to prompt
prepareVideo now requests 480x270 @ 24fps instead of the previous
120x68 @ 12fps thumbnail, so playback actually looks like playback
rather than a postage stamp.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>