Fix database session context manager errors

- Add explicit commit/rollback in session dependencies
- Prevents RuntimeError: generator didn't stop after athrow()
- Ensures proper transaction cleanup on exceptions

src/server/utils/dependencies.py

@@ -130,14 +130,15 @@ async def get_database_session() -> AsyncGenerator:
             detail="Database functionality not installed"
         )
     
-    try:
-        async with get_db_session() as session:
+    async with get_db_session() as session:
+        try:
             yield session
-    except RuntimeError as e:
-        raise HTTPException(
-            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
-            detail=f"Database not available: {str(e)}"
-        )
+            # Auto-commit on successful completion
+            await session.commit()
+        except Exception:
+            # Auto-rollback on error
+            await session.rollback()
+            raise
 
 
 async def get_optional_database_session() -> AsyncGenerator:
@@ -169,12 +170,16 @@ async def get_optional_database_session() -> AsyncGenerator:
         yield None
         return
     
-    try:
-        async with get_db_session() as session:
+    # Use get_db_session context manager properly
+    async with get_db_session() as session:
+        try:
             yield session
-    except (ImportError, RuntimeError):
-        # Database became unavailable - this shouldn't happen but handle it
-        yield None
+            # Auto-commit on successful completion
+            await session.commit()
+        except Exception:
+            # Auto-rollback on error
+            await session.rollback()
+            raise
 
 
 def get_current_user(