Refactor database connection: move connection logic to db.py and update imports in app.py and schema.py

app.py

@@ -1,6 +1,6 @@
 
 from fastapi import FastAPI, HTTPException
-from sql import connect_to_database, disconnect_from_database, database
+from db import connect_to_database, disconnect_from_database, database
 from schema import rca_results, RCAResult
 import logging
 

sql.py → db.py

@@ -57,4 +57,4 @@ async def disconnect_from_database():
         logger.info("Successfully disconnected from the database.")
     except Exception as e:
         logger.error("Error disconnecting from the database: %s", e)
-        raise
+        raise

schema.py

@@ -10,7 +10,7 @@ import sqlalchemy
 from sqlalchemy import (
     Table, Column, String, Integer, DateTime, ForeignKey, Text, func, JSON
 )
-from sql import metadata
+from db import metadata
 
 
 rca_results = Table(