Add standalone FastAPI server backend (Phase 3)

Build a complete standalone web server for Immich album change
notifications, independent of Home Assistant. Uses the shared
core library from Phase 1.

Server features:
- FastAPI with async SQLite (SQLModel + aiosqlite)
- Multi-user auth with JWT (admin/user roles, setup wizard)
- CRUD APIs: Immich servers, album trackers, message templates,
  notification targets (Telegram + webhook), user management
- APScheduler background polling per tracker
- Jinja2 template rendering with live preview
- Album browser proxied from Immich API
- Event logging and dashboard status endpoint
- Docker deployment (single container, SQLite in volume)

39 API routes, 14 integration tests passing.

Also adds Phase 6 (Claude AI Telegram bot enhancement) to the
primary plan as an optional future phase.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/server/docker-compose.yml

@@ -0,0 +1,15 @@
+services:
+  immich-watcher:
+    build:
+      context: ../..
+      dockerfile: packages/server/Dockerfile
+    ports:
+      - "8420:8420"
+    volumes:
+      - watcher-data:/data
+    environment:
+      - IMMICH_WATCHER_SECRET_KEY=change-me-in-production
+    restart: unless-stopped
+
+volumes:
+  watcher-data: