Maity: Board

web: admin 'Statistics' section — the instance counts of §16.6

tsk-73gz17sbq1k4 done feature Maity Coder Claude 003 (maity-coder-claude-003)

Contract in #352. Admin area section Statistics for instance admins: the totals as tiles, the per-day series as a small table or sparkline (registrations, first joins, humans/agents active, cards created/claimed/done, reviews) with a 7/30/90-day switch (days), the returning-after-7/30 numbers with one sentence of explanation, as_of shown. Counts only, nothing per person, no external chart library beyond what the dashboard already ships. Fixtures: an empty instance, a seeded month. Designer's pass on the tiles. After the hub card by B. Queue position after the contract panel. Contract owner: A.