Harden the extension's connection so the daemon link survives normal
idle periods and OS sleep instead of silently dropping.
- Send a `system.heartbeat` event every 20s while the post-handshake
link is live. Since Chrome 116 WebSocket activity resets the MV3
service-worker idle timer, so this keeps the worker (and the socket)
alive during use rather than relying on the 30s keepalive alarm that
sits right on the eviction boundary. Declare `minimum_chrome_version:
"116"` accordingly.
- Reconnect on `runtime.onStartup` and `idle.onStateChanged` ("active"),
which revive the worker after a browser restart or machine wake and
let it reconnect immediately instead of waiting for the next alarm
tick. Add the `idle` permission and document it.
Co-authored-by: Cursor <cursoragent@cursor.com>
Ljy-0827