Add audit logging for admin settings changes, rate limit config updates, anomaly detection config changes (skipped due to no UI), and version cleanup settings updates. Implement logging via central logAdminAction helper and integrate into AdminSettings, VersionCleanupSettings, and RateLimitAlerts mutations (create, update, delete).
Implement monitor-rate-limits edge function to compare metrics against alert configurations, trigger notifications, and record alerts; update config and groundwork for admin UI integration.