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/database/__init__.py

@@ -0,0 +1,24 @@
+"""Database package."""
+
+from .engine import get_session, init_db
+from .models import (
+    AlbumState,
+    AlbumTracker,
+    EventLog,
+    ImmichServer,
+    MessageTemplate,
+    NotificationTarget,
+    User,
+)
+
+__all__ = [
+    "get_session",
+    "init_db",
+    "AlbumState",
+    "AlbumTracker",
+    "EventLog",
+    "ImmichServer",
+    "MessageTemplate",
+    "NotificationTarget",
+    "User",
+]

packages/server/src/immich_watcher_server/database/engine.py

@@ -0,0 +1,36 @@
+"""Database engine and session management."""
+
+from collections.abc import AsyncGenerator
+
+from sqlmodel import SQLModel
+from sqlmodel.ext.asyncio.session import AsyncSession
+from sqlalchemy.ext.asyncio import AsyncEngine, create_async_engine
+
+from ..config import settings
+
+_engine: AsyncEngine | None = None
+
+
+def get_engine() -> AsyncEngine:
+    """Get or create the async database engine."""
+    global _engine
+    if _engine is None:
+        _engine = create_async_engine(
+            settings.effective_database_url,
+            echo=settings.debug,
+        )
+    return _engine
+
+
+async def init_db() -> None:
+    """Create all database tables."""
+    engine = get_engine()
+    async with engine.begin() as conn:
+        await conn.run_sync(SQLModel.metadata.create_all)
+
+
+async def get_session() -> AsyncGenerator[AsyncSession, None]:
+    """Yield an async database session (FastAPI dependency)."""
+    engine = get_engine()
+    async with AsyncSession(engine) as session:
+        yield session

packages/server/src/immich_watcher_server/database/models.py

@@ -0,0 +1,112 @@
+"""SQLModel database table definitions."""
+
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from typing import Any
+
+from sqlmodel import JSON, Column, Field, SQLModel
+
+
+def _utcnow() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+class User(SQLModel, table=True):
+    """Application user."""
+
+    id: int | None = Field(default=None, primary_key=True)
+    username: str = Field(index=True, unique=True)
+    hashed_password: str
+    role: str = Field(default="user")  # "admin" or "user"
+    created_at: datetime = Field(default_factory=_utcnow)
+
+
+class ImmichServer(SQLModel, table=True):
+    """Immich server connection."""
+
+    __tablename__ = "immich_server"
+
+    id: int | None = Field(default=None, primary_key=True)
+    user_id: int = Field(foreign_key="user.id")
+    name: str = Field(default="Immich")
+    url: str
+    api_key: str
+    external_domain: str | None = None
+    created_at: datetime = Field(default_factory=_utcnow)
+
+
+class NotificationTarget(SQLModel, table=True):
+    """Notification destination (Telegram chat, webhook URL)."""
+
+    __tablename__ = "notification_target"
+
+    id: int | None = Field(default=None, primary_key=True)
+    user_id: int = Field(foreign_key="user.id")
+    type: str  # "telegram" or "webhook"
+    name: str
+    config: dict[str, Any] = Field(default_factory=dict, sa_column=Column(JSON))
+    created_at: datetime = Field(default_factory=_utcnow)
+
+
+class MessageTemplate(SQLModel, table=True):
+    """Jinja2 message template."""
+
+    __tablename__ = "message_template"
+
+    id: int | None = Field(default=None, primary_key=True)
+    user_id: int = Field(foreign_key="user.id")
+    name: str
+    body: str = Field(default="")
+    is_default: bool = Field(default=False)
+    created_at: datetime = Field(default_factory=_utcnow)
+
+
+class AlbumTracker(SQLModel, table=True):
+    """Album change tracker configuration."""
+
+    __tablename__ = "album_tracker"
+
+    id: int | None = Field(default=None, primary_key=True)
+    user_id: int = Field(foreign_key="user.id")
+    server_id: int = Field(foreign_key="immich_server.id")
+    name: str
+    album_ids: list[str] = Field(default_factory=list, sa_column=Column(JSON))
+    event_types: list[str] = Field(
+        default_factory=lambda: ["assets_added"],
+        sa_column=Column(JSON),
+    )
+    target_ids: list[int] = Field(default_factory=list, sa_column=Column(JSON))
+    template_id: int | None = Field(default=None, foreign_key="message_template.id")
+    scan_interval: int = Field(default=60)  # seconds
+    enabled: bool = Field(default=True)
+    quiet_hours_start: str | None = None  # "HH:MM"
+    quiet_hours_end: str | None = None  # "HH:MM"
+    created_at: datetime = Field(default_factory=_utcnow)
+
+
+class AlbumState(SQLModel, table=True):
+    """Persisted album state for change detection across restarts."""
+
+    __tablename__ = "album_state"
+
+    id: int | None = Field(default=None, primary_key=True)
+    tracker_id: int = Field(foreign_key="album_tracker.id")
+    album_id: str
+    asset_ids: list[str] = Field(default_factory=list, sa_column=Column(JSON))
+    pending_asset_ids: list[str] = Field(default_factory=list, sa_column=Column(JSON))
+    last_updated: datetime = Field(default_factory=_utcnow)
+
+
+class EventLog(SQLModel, table=True):
+    """Log of detected album change events."""
+
+    __tablename__ = "event_log"
+
+    id: int | None = Field(default=None, primary_key=True)
+    tracker_id: int = Field(foreign_key="album_tracker.id")
+    event_type: str
+    album_id: str
+    album_name: str
+    details: dict[str, Any] = Field(default_factory=dict, sa_column=Column(JSON))
+    created_at: datetime = Field(default_factory=_utcnow)