Add Rich Presence infrastructure to ConnectionManager:
- Four new Maps: userActivities, userShowActivity, userStatuses, lastActivityUpdate
- Public accessors: set/get/clear activities, showActivity, status, rate limit check
- Cleanup in finalizeDisconnect() and forceDisconnectUser()
- Cache showActivity and status from DB at auth time in buildReadyPayload()
- Assemble userActivities snapshot in ready payload with customStatus fallback
- Include activities: [] in offline presence_update broadcast
Jannis Braun
d4366a2207