fix: log real PostgreSQL startup error instead of silently falling back

app_part1.py

@@ -88,7 +88,12 @@ async def init_db_pool() -> asyncpg.Pool:
 async def lifespan(app: FastAPI):
     global db_pool
     try:
+        try:
         db_pool = await init_db_pool()
+        logger.info("Database pool initialized successfully.")
+    except Exception as db_err:
+        logger.error(f"Database pool FAILED: {db_err}")
+        db_pool = None
         logger.info("Database pool initialized.")
     except Exception as exc:
         logger.error("Failed to initialize Postgres pool. Falling back to memory: %s", exc)