refactor: remove unused authentication files and dependencies; update package.json to streamline dependencies and improve project structure

packages/backend/convex/convex.config.ts

@@ -1,7 +1,4 @@
 import { defineApp } from "convex/server";
-import betterAuth from "./betterAuth/convex.config";
-
 const app = defineApp();
-app.use(betterAuth);
 
 export default app;