Fix: Propagate app_user_email when a global context already exists

Signed-off-by: Ilia Manolov <iliamanolov@outlook.com>

Author: IliaMManolov

mcpgateway/services/tool_service.py

@@ -1222,6 +1222,8 @@ async def invoke_tool(
             gateway_id = getattr(tool, "gateway_id", None)
             if gateway_id and isinstance(gateway_id, str):
                 global_context.server_id = gateway_id
+            if gateway_id and isinstance(app_user_email, str):
+                global_context.user = app_user_email
         else:
             # Create new context (fallback when middleware didn't run)
             request_id = uuid.uuid4().hex