Bugfix release.

Fixes:
• Resolves audio dropout on embedded videos from sites whose CDN omits CORS
headers (e.g., X / Twitter video overlays). Volume Balance now automatically
switches to a compatible mode on such elements — the master volume slider
still works, but the compressor is skipped on those videos (not technically
feasible due to a browser security limit on cross-origin media).
• Prevents a brief mute on autoplay videos that start before the browser's
AudioContext has been activated by a user gesture.

Simplified to one global compressor + master volume applied on every site (no more per-site
assignments). Fixes a bug where the master volume slider position was loaded from storage but
the actual audio level didn't apply until the slider was nudged. Cleaner UI, smaller code
footprint.