build: update base URL and router configuration for custom domain

Update Vite config and router basename to use root path for production
Add CNAME file for custom domain deployment

vite.config.ts

@@ -6,7 +6,7 @@ import tailwindcss from "@tailwindcss/vite"
 // https://vite.dev/config/
 export default defineConfig({
   plugins: [react(), tailwindcss()],
-  base: process.env.NODE_ENV === 'production' ? '/react-template/' : '/',
+  base: "/",
   resolve: {
     alias: {
       "@": fileURLToPath(new URL("./src", import.meta.url)),