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/src/immich_watcher_server/main.py

@@ -0,0 +1,94 @@
+"""FastAPI application entry point."""
+
+from __future__ import annotations
+
+import logging
+from contextlib import asynccontextmanager
+from pathlib import Path
+
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.staticfiles import StaticFiles
+
+from .config import settings
+from .database.engine import init_db
+from .services.scheduler import start_scheduler, stop_scheduler
+
+from .auth.routes import router as auth_router
+from .api.servers import router as servers_router
+from .api.trackers import router as trackers_router
+from .api.templates import router as templates_router
+from .api.targets import router as targets_router
+from .api.users import router as users_router
+from .api.status import router as status_router
+
+logging.basicConfig(
+    level=logging.DEBUG if settings.debug else logging.INFO,
+    format="%(asctime)s %(levelname)s [%(name)s] %(message)s",
+)
+_LOGGER = logging.getLogger(__name__)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """Application lifespan: startup and shutdown."""
+    # Startup
+    settings.data_dir.mkdir(parents=True, exist_ok=True)
+    await init_db()
+    _LOGGER.info("Database initialized at %s", settings.effective_database_url)
+
+    await start_scheduler()
+
+    yield
+
+    # Shutdown
+    await stop_scheduler()
+
+
+app = FastAPI(
+    title="Immich Watcher",
+    description="Standalone Immich album change notification server",
+    version="0.1.0",
+    lifespan=lifespan,
+)
+
+# CORS for frontend dev server
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+# API routes
+app.include_router(auth_router)
+app.include_router(servers_router)
+app.include_router(trackers_router)
+app.include_router(templates_router)
+app.include_router(targets_router)
+app.include_router(users_router)
+app.include_router(status_router)
+
+# Serve frontend static files if available
+_frontend_dist = Path(__file__).parent / "frontend"
+if _frontend_dist.is_dir():
+    app.mount("/", StaticFiles(directory=_frontend_dist, html=True), name="frontend")
+
+
+@app.get("/api/health")
+async def health():
+    """Health check endpoint."""
+    return {"status": "ok", "version": "0.1.0"}
+
+
+def run():
+    """Run the server (entry point for `immich-watcher` CLI command)."""
+    import uvicorn
+
+    uvicorn.run(
+        "immich_watcher_server.main:app",
+        host=settings.host,
+        port=settings.port,
+        reload=settings.debug,
+    )