Small tapir slice to make the gate measurable as written: append-only
login_events (RLS, per-user-per-day throttle) + a union query over reads
(login_events) and acts (summary_actions) for distinct-active-weeks. Carries the
honesty caveats (unprompted not measurable; data accrues from deploy; week-bucket
noise at low N) and the delete-cascade footgun (no FK, needs explicit delete +
test) from the prior delete work. Out of scope: analytics, prompt-tracking,
dashboards.
