The update progress modal was stuck showing 'initializing' even after the
backend restarted and websocket reconnected. Users could see the connection
status badge reconnecting behind the modal, but the modal never cleared.
Now the modal:
- Watches websocket connection status during update
- Detects when backend disconnects and reconnects
- Verifies health after reconnection
- Automatically reloads the page when update is complete
- Shows clearer messaging about restart progress
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