Version 1.1 replaces the WebRTC peer connection with a small WebSocket relay
you can deploy yourself, and encrypts everything that travels over it.

New
* Playback state now travels over a Cloudflare Worker relay instead of WebRTC,
so sessions connect in the network situations where the old direct peer
connection silently failed.
* End-to-end encryption. Peers agree a key with ECDH P-256 and seal each
update with AES-GCM, so the relay forwards bytes it cannot read and keeps
no history.
* The relay is never told the room code, only a stretched hash of it.
* New "Relay server" setting in the popup, which point the extension at your own
relay (see server/ in the repository) or at a local one for testing.
* Room codes expanded to 9 characters (ABC-DEF-GHI).
* Sync scope toggle: This Page, All tabs, or Off.

Fixed
* Incoming pause/play/seek was not always applied to the receiving video.
* Play and pause could bounce between peers in a loop; a change now settles
after one hop.
* Connection failures are reported in the popup instead of leaving the button
spinning, and closing a session no longer leaves an orphaned socket behind.
* Idle sessions are no longer dropped by a mishandled heartbeat.

Removed
* The bundled simple-peer library and the "offscreen" permission, both of
which existed only for WebRTC.