feat: add SQLite persistence models

app/main.py

@@ -1,6 +1,7 @@
 from fastapi import FastAPI
 
 from app.config import Settings, get_settings
+from app.db.session import create_db_engine, create_session_factory, initialize_schema
 
 
 def create_app(settings: Settings | None = None) -> FastAPI:
@@ -12,6 +13,11 @@ def create_app(settings: Settings | None = None) -> FastAPI:
     app = FastAPI(title="MyWhoosh Garmin Sync")
     app.state.settings = resolved
 
+    engine = create_db_engine(resolved.database_url)
+    initialize_schema(engine)
+    app.state.db_engine = engine
+    app.state.session_factory = create_session_factory(engine)
+
     @app.get("/healthz")
     def healthz() -> dict[str, str]:
         return {"status": "ok"}