refactor starlette as API, langgraph from openrouter

app.py

@@ -0,0 +1,29 @@
+from starlette.applications import Starlette
+from starlette.routing import Route
+from controllers import create_chat, post_message, stream_response
+from starlette.middleware import Middleware
+from starlette.middleware.cors import CORSMiddleware
+
+middleware = [
+    Middleware(
+        CORSMiddleware,
+        allow_origins=["*"],            # change to ["http://localhost:3000"] etc. in prod
+        allow_credentials=True,
+        allow_methods=["*"],
+        allow_headers=["*"],
+    )
+]
+
+routes = [
+    Route("/chats", create_chat, methods=["POST"]),
+    Route("/chats/{chat_id:str}/messages", post_message, methods=["POST"]),
+    Route("/chats/{chat_id:str}/stream",   stream_response, methods=["GET"]),
+]
+
+
+application = Starlette(debug=True, routes=routes, middleware=middleware)
+
+# ----------------- Run -----------------
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run(application, host="0.0.0.0", port=8000)