fix: add health endpoint to agui langgraph fastapi

Author: ranst91

typescript-sdk/integrations/langgraph/python/ag_ui_langgraph/endpoint.py

@@ -24,4 +24,14 @@ async def event_generator():
         return StreamingResponse(
             event_generator(),
             media_type=encoder.get_content_type()
-        )
+        )
+
+    @app.get(f"{path}/health")
+    def health():
+        """Health check."""
+        return {
+            "status": "ok",
+            "agent": {
+                "name": agent.name,
+            }
+        }