Fix app.py imports to use proxy server instead of playground

app.py

@@ -1,11 +1,12 @@
 from fastapi import FastAPI
-from litellm.playground_server import add_playground_routes
+from litellm.proxy.proxy_server import ProxyServer
+from litellm.proxy.proxy_server import app as proxy_app
 
 app = FastAPI()
 
-# Add LiteLLM Playground UI at `/docs`
-add_playground_routes(app)
+# Mount the LiteLLM Proxy server
+app.mount("/proxy", proxy_app)
 
 @app.get("/")
 def home():
-    return {"message": "LiteLLM UI is running! Visit /docs"}
+    return {"message": "LiteLLM Server is running! Visit /proxy/docs for the API documentation"}