fix: correct build output path and guard devtools plugin in production

vite.config.ts

@@ -6,9 +6,16 @@ import { tanstackStart } from '@tanstack/react-start/plugin/vite'
 import viteReact from '@vitejs/plugin-react'
 import tailwindcss from '@tailwindcss/vite'
 
+const isProd = process.env['NODE_ENV'] === 'production'
+
 const config = defineConfig({
   resolve: { tsconfigPaths: true },
-  plugins: [devtools(), tailwindcss(), tanstackStart(), viteReact()],
+  plugins: [
+    !isProd && devtools(),
+    tailwindcss(),
+    tanstackStart(),
+    viteReact(),
+  ].filter(Boolean),
 })
 
 export default config