Frontend:
- P0: Replace constant estimateSize(40px) with content-based estimation
using line count and reply presence for accurate virtual list scroll
- P1: Replace Shadow DOM custom elements with styled spans for @mentions,
eliminating expensive attachShadow calls per mention instance
- P1: Remove per-message ResizeObserver (one per bubble), replace with
static inline toolbar layout to avoid observer overhead
- P2: Fix WS token re-fetch on every room switch by preserving token
across navigation and not clearing activeRoomIdRef on cleanup
Backend:
- P1: Fix reaction check+insert race condition by moving into transaction
instead of separate query + on-conflict insert
- P2: Fix N+1 queries in get_mention_notifications with batch fetch
for users and rooms using IN clauses
- P2: Update room_last_activity in broadcast_stream_chunk to prevent
idle room cleanup during active AI streaming
- P3: Use enum comparison instead of to_string() in room_member_leave
