- Connection cards on the Stats page now show the **username** of the connected user in a new User column (between IP Address and Connected). The username is resolved from the user store using the `user_id` stored in Redis client metadata; unauthenticated connections display "Anonymous". (Closes#766)
- `ip_address` and `user_id` were not included in the client info returned by `get_detailed_channel_info()` despite being available in the Redis hash. Both fields are now extracted and returned. (Closes#586)
- Change ChannelState.PRE_ACTIVE from list to frozenset (immutable,
O(1) membership tests, no risk of silent mutation)
- Add optional client_ids parameter to ClientManager.remove_ghost_clients()
so callers that have already fetched SMEMBERS can pass it through,
eliminating a redundant Redis round-trip
- Pass pre-fetched client_ids from get_basic_channel_info() into
remove_ghost_clients() to remove the duplicate SMEMBERS call
- Write ERROR via ownership check OR state guard fallback when ownership TTL expired during retries
- Add INITIALIZING to cleanup task grace period monitoring
- Validate client SET entries against metadata hashes in orphaned channel cleanup; remove ghosts and clean up when no real clients remain
- Stats page self-heals by removing ghost SET entries on read
- Extract remove_ghost_clients() helper to ClientManager
- Add ChannelState.PRE_ACTIVE constant
- Fix 6 pre-existing NonOwnerWorkerKeepalive test failures
