default frontend api to relative URL

frontend/src/utils/constants.js

 export const API_BASE =
-  import.meta.env.VITE_API_BASE || "http://localhost:3001/api";
+  import.meta.env.VITE_API_BASE || "/api";
 
 export const AUTH_USER = "anythingllm_user";
 export const AUTH_TOKEN = "anythingllm_authToken";