fix: reorder routes - mount Gradio after API routes to avoid 404

- Move app.mount('/') to end of file after all @app decorators
- This ensures /a2a/v1, /health, /.well-known/* are not shadowed by Gradio catch-all
- Standard FastAPI pattern for mixed API+Gradio apps

main.py

@@ -236,10 +236,6 @@ def build_gradio_ui() -> gr.Blocks:
 # FastAPI app
 app = FastAPI(title="A2A Cloud Coder Agent")
 
-# Mount Gradio app at root
-gradio_app = build_gradio_ui()
-app.mount("/", gradio_app.app)
-
 # A2A endpoint
 app.post("/a2a/v1")(handle_a2a_message)
 
@@ -257,12 +253,6 @@ async def health() -> JSONResponse:
         }
     )
 
-# Root endpoint for HF space page
-@app.get("/")
-async def root() -> JSONResponse:
-    return JSONResponse({"service": "A2A Cloud Coder", "status": "running"})
-
-
 # Agent card endpoint
 @app.get("/.well-known/agent-card.json")
 async def agent_card(request: Request) -> JSONResponse:
@@ -290,6 +280,11 @@ async def oauth_client() -> JSONResponse:
     )
 
 
+# Build Gradio UI and mount as catch-all (after all API routes)
+gradio_app = build_gradio_ui()
+app.mount("/", gradio_app.app)
+
+
 if __name__ == "__main__":
     import uvicorn
     print("🚀 Starting uvicorn on port", int(os.getenv("PORT", 7860)))