refactored: to utilise the google adk and production grade agent

app/agent.py

@@ -1,5 +1,6 @@
 """gcp_solution_architecture_agent: Starlette application wiring & CLI entrypoint."""
 
+from contextlib import asynccontextmanager
 import logging
 import click
 import uvicorn
@@ -7,8 +8,10 @@ from starlette.applications import Starlette
 from starlette.routing import Route
 
 from app.config import get_settings
+from app.database import get_db_manager
 from app.workflows.routes import (
     get_card,
+    get_session_route,
     health_check,
     run_workflow,
     validate_artifacts_route,
@@ -27,11 +30,20 @@ routes = [
     Route("/card", get_card, methods=["GET"]),
     Route("/generate", run_workflow, methods=["POST"]),
     Route("/validate", validate_artifacts_route, methods=["POST"]),
+    Route("/sessions/{session_id}", get_session_route, methods=["GET"]),
 ]
 
+@asynccontextmanager
+async def lifespan(app: Starlette):
+    """Initialize PostgreSQL database schema on server startup."""
+    logger.info("Initializing PostgreSQL database persistence...")
+    get_db_manager()
+    yield
+
 app = Starlette(
     debug=True,
     routes=routes,
+    lifespan=lifespan,
 )