main ← pacharanero:fix/live-background-blur-brave
Previously, Live background blur failed in Brave because its hidden video was pl…ayed without being attached to the page.
This change attaches the video invisibly before playback and removes it during cleanup, including when startup fails.
Fixes https://meta.discourse.org/t/-/415845
### Testing
- Tested locally in Brave with Shields on and off: blur works in both cases.
- Confirmed repeated blur toggles, camera shutdown, and room exit work normally.
- ESLint and Prettier pass.