feat: add local auth billing and usage management

next.config.ts

@@ -1,6 +1,9 @@
 import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
+  // Keep dev artifacts separate from production builds. Running `next build`
+  // while a dev server is alive must not invalidate the dev server's chunks.
+  distDir: process.env.NODE_ENV === "development" ? ".next-dev" : ".next",
   devIndicators: false,
   experimental: {
     serverActions: {