Add admin configuration system and M3 content automation

Admin Configuration System:
- Add registry_settings table to database schema
- Create settings.py module with 17 configurable settings across 5 categories
  (vetting, similarity, sync, moderation, rate_limits)
- Add admin API endpoints for settings management (list/get/set/reset)
- Create admin settings web UI page with tabbed categories
- Add CLI commands: cmdforge registry config list/get/set
- Wire settings page link into admin index

M3 Content Automation Scripts:
- scrutiny.py: Quality scoring with 5 weighted checks
- similarity.py: TF-IDF based duplicate detection
- vet_pipeline.py: Combined vetting with auto-decision logic
- fabric_sync.py: Scheduled Fabric pattern synchronization
- fabric-sync.service/timer: systemd units for scheduled sync

Settings available:
- Vetting thresholds (approve/reject) and check weights
- Similarity detection thresholds (duplicate/similar/related)
- Fabric sync configuration (enabled, interval, auto-approve)
- Moderation settings (require review, auto-approve private)
- Rate limiting configuration

Co-Authored-By: Claude Opus 4.5 <[email protected]>

scripts/fabric-sync.timer

@@ -0,0 +1,14 @@
+[Unit]
+Description=Daily Fabric Pattern Sync for CmdForge
+Documentation=https://pages.brrd.tech/rob/cmdforge/
+
+[Timer]
+# Run daily at 3 AM
+OnCalendar=*-*-* 03:00:00
+# Randomize start time by up to 1 hour to avoid thundering herd
+RandomizedDelaySec=3600
+# Run immediately if we missed a scheduled run
+Persistent=true
+
+[Install]
+WantedBy=timers.target