docs: reorganize documentation structure for better context efficiency

Reorganization changes:
1. Moved from root → docs/:
   - QUICKSTART.md
   - QUICK_TEST.md
   - WEBRTC_TESTING_GUIDE.md

2. Created docs/archive/ and moved archival files:
   - COMPLETED.md (completed tasks archive)
   - PHASE_1.5.md (historical phase documentation)
   - RESOURCES.md (learning resources)
   - SECURITY_AUDIT.md (security audit)
   - ADMIN_CLI.md (CLI documentation)

3. Updated all references in:
   - README.md
   - docs/CONTEXT.md
   - docs/TODO.md
   - docs/SESSION_CONTEXT.md
   - docs/DEPLOYMENT.md
   - docs/QUICK_TEST.md

Active docs/ now contains only essential files:
- SESSION_CONTEXT.md (primary for context restoration)
- TODO.md
- CONTEXT.md
- ARCHITECTURE.md
- DEPLOYMENT.md
- MONITORING.md
- QUICKSTART.md
- QUICK_TEST.md
- WEBRTC_TESTING_GUIDE.md

Benefits:
- Reduced token usage when reading docs/ for context
- Clear separation between active and archived documentation
- Better organization for future maintenance

docs/DEPLOYMENT.md

@@ -273,7 +273,7 @@ Logs are configured with rotation:
 - [ ] Configure firewall (allow only 80, 443, 22)
 - [ ] Set up automated backups
 - [ ] Configure monitoring/alerting
-- [ ] Review security audit report (`docs/SECURITY_AUDIT.md`)
+- [ ] Review security audit report (`docs/archive/SECURITY_AUDIT.md`)
 
 ### After Deployment
 
@@ -442,7 +442,7 @@ docker exec spotlightcam-db-prod pg_dump -U spotlightcam spotlightcam > backup.s
 
 For issues:
 1. Check logs: `docker compose logs`
-2. Review security audit: `docs/SECURITY_AUDIT.md`
+2. Review security audit: `docs/archive/SECURITY_AUDIT.md`
 3. Check session context: `docs/SESSION_CONTEXT.md`
 4. Review phase documentation: `docs/PHASE_*.md`