ADMIN-OPS-001 — paginated account list with search (admin-gated)

List platform accounts, newest first, with per-account activity counts.

Per row: id, email, plan, is_paid (stripe_subscription_id present), is_active, email_verified, agent_count, run_count, created_at, last_active (best-effort — max of the account's last run and last successful login).

N+1 avoidance: the agent counts, run counts, last-run and last-login timestamps are each computed in ONE grouped query over the page's user-id set, not per-row.

Auth: anonymous → 401, non-admin → 403, admin → 200. Flag-off → 404 (rule #4). Pagination caps at 100 (rule #9).

Privacy: password hashes / stripe ids / tokens are NEVER serialized — see _account_row.