chore: enhance frontend configuration for backend integration

- Added environment variables for backend URLs in the Dockerfile to facilitate dynamic configuration.
- Updated Next.js configuration to include rewrites for health and API endpoints, improving backend connectivity.
- Modified settings page to handle backend URL locking and normalization, enhancing user experience and data integrity.

next.config.ts

@@ -1,7 +1,18 @@
 import type { NextConfig } from "next";
 
+const backendInternalUrl = (process.env.BACKEND_INTERNAL_URL ?? "http://127.0.0.1:8000").replace(
+  /\/$/,
+  "",
+);
+
 const nextConfig: NextConfig = {
   output: "standalone",
+  async rewrites() {
+    return [
+      { source: "/health", destination: `${backendInternalUrl}/health` },
+      { source: "/api/:path*", destination: `${backendInternalUrl}/api/:path*` },
+    ];
+  },
 };
 
 export default nextConfig;