Show Lichess restarting / maintenance Messages

[EmmetSchuler]

Add support for messages like "Lichess will restart in x amount of minutes" and "Lichess is undergoing scheduled maintenance."

As of now, when Lichess is under scheduled maintenance we get errors like

[veloce]

This feature is the equivalent of the announce in the old app:

https://github.com/lichess-org/lichobile/blob/master/src/announce.ts https://github.com/lichess-org/lichobile/blob/8b17f5e93f415f81855a81cbc8365512591e9d4d/src/socket/index.ts#L52

[bhavikpanchal1111]

I am willing to solve this issue, so I would need developer access.

[veloce]

WS API: {"t":"announce","d":{"msg":"Lichess will restart","date":"2025-08-26T19:53:00.472875264Z"}}

The d part is also returned by /api/account in an announce field (TBD).

[veloce]

The d part is also returned by /api/account in an announce field (TBD).

@ornicar we still need this to add this feature on mobile.