feat: Phase 4+5 — admin storage UI, backend proxy, CLAUDE.md enforcement

- backend/app/routers/storage_config.py: 5 admin-only endpoints proxying
  storage-service config + migration API (GET/PATCH/POST/DELETE)
- backend/app/main.py: register storage_config router
- frontend/src/api/client.ts: StorageStatus, MigrationStatus,
  StorageBackendConfig interfaces + 5 API functions
- frontend/src/pages/StorageAdminPage.tsx: full admin UI — backend health
  dot, driver selector (local/S3/WebDAV), conditional credential fields,
  Test & Migrate button, live 2s-poll migration progress bar, Cancel
- frontend/src/App.tsx: /admin/storage route (AdminRoute guard)
- CLAUDE.md: storage enforcement rule, updated Docker tables (6 services,
  3 volumes), §20 in merge checklist
- backend/CLAUDE.md, frontend/CLAUDE.md, doc-service/CLAUDE.md,
  ai-service/CLAUDE.md: updated to reflect storage-service integration
- tests/ALL_TESTS.md + tests/storage-service_tests.md: §20 (20 tests)
- backend/STATUS.md, frontend/STATUS.md: updated with new endpoints/routes
- changelog/2026-04-20_storage-service.md: full change log

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

features/ai-service/CLAUDE.md

@@ -22,7 +22,8 @@ features/ai-service/
 │   │   ├── queue.py               ← GET /queue/status, /pause, /resume, /cancel/{id}
 │   │   └── plugin.py              ← GET /plugin/manifest (access rules for ai-service-admin group)
 │   └── services/
-│       └── queue.py               ← Priority queue (CRITICAL > HIGH > NORMAL)
+│       ├── queue.py               ← Priority queue (CRITICAL > HIGH > NORMAL)
+│       └── config_reader.py       ← Reads ai_service_config.json from storage-service config bucket (30 s TTL cache)
 ├── Dockerfile                     ← python:3.12-slim, non-root user 1001
 └── STATUS.md
 ```