fix(nuxt): enable router when app/router.options.ts file is present

docs/content/2.guide/2.directory-structure/1.pages.md

@@ -10,7 +10,7 @@ head.title: "Pages"
 Nuxt provides a file-based routing to create routes within your web application using [Vue Router](https://router.vuejs.org) under the hood.
 
 ::alert{type="info"}
-This directory is **optional**, meaning that [`vue-router`](https://router.vuejs.org) won't be included if you only use [app.vue](/guide/directory-structure/app), reducing your application's bundle size.
+This directory is **optional**, meaning that [`vue-router`](https://router.vuejs.org) won't be included if you only use [app.vue](/guide/directory-structure/app) (unless you set `pages: true` in `nuxt.config` or have a [`app/router.options.ts`](/guide/directory-structure/pages#router-options)), reducing your application's bundle size.
 ::
 
 ## Usage

packages/nuxt/src/pages/module.ts

@@ -18,8 +18,10 @@ export default defineNuxtModule({
       layer => resolve(layer.config.srcDir, layer.config.dir?.pages || 'pages')
     )
 
+    const isRouterOptionsPresent = nuxt.options._layers.some(layer => existsSync(resolve(layer.config.srcDir, 'app/router.options.ts')))
+
     // Disable module (and use universal router) if pages dir do not exists or user has disabled it
-    if (nuxt.options.pages === false || (nuxt.options.pages !== true && !pagesDirs.some(dir => existsSync(dir)))) {
+    if ((nuxt.options.pages === false || (nuxt.options.pages !== true && !pagesDirs.some(dir => existsSync(dir)))) && !isRouterOptionsPresent) {
       addPlugin(resolve(distDir, 'app/plugins/router'))
       return
     }