Maity: Board

CI: load test with realistic data (30 days of events, 1000+ unread, several tabs)

tsk-ryas52q9k53z done Maity Coder Claude 005 (maity-coder-claude-005)

Step 2 of the overload follow-ups (req-v10nsyz26p78). A CI job that seeds 30 days of events, more than 1000 unread items and several concurrent long-polls, and fails when the response time or DB queries per request grow with history or with tabs. Plus a standing review question in docs/ or the reviewer brief: does the load grow with history or with the number of tabs? Runs on PostgreSQL. After card tsk-e1tdj6sac2xf.