fix(nuxt): ensure .output directory is marked as an output (#26414)

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## Current Behavior
<!-- This is the behavior we have today -->
Nuxt states that the `.output` folder is created with a production
build, regardless of the `buildDir` set in the `nuxt.config.ts` file.
We do not have this folder listed as an output and therefore it is not
cached and restored correctly


## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->
Ensure the `.output` folder is listed correctly as an output

## Related Issue(s)
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merged. -->

Fixes #

packages/nuxt/src/plugins/__snapshots__/plugin.spec.ts.snap

@@ -26,6 +26,7 @@ exports[`@nx/nuxt/plugin not root project should create nodes 1`] = `
           },
           "outputs": [
             "{workspaceRoot}/dist/my-app/.nuxt",
+            "{projectRoot}/.output",
           ],
         },
         "acme-serve-static": {
@@ -57,6 +58,7 @@ exports[`@nx/nuxt/plugin not root project should create nodes 1`] = `
           },
           "outputs": [
             "{workspaceRoot}/dist/my-app/.nuxt",
+            "{projectRoot}/.output",
           ],
         },
         "my-serve": {
@@ -97,6 +99,7 @@ exports[`@nx/nuxt/plugin root project should create nodes 1`] = `
           },
           "outputs": [
             "dist/my-app/.nuxt",
+            "{projectRoot}/.output",
           ],
         },
         "build-static": {
@@ -119,6 +122,7 @@ exports[`@nx/nuxt/plugin root project should create nodes 1`] = `
           },
           "outputs": [
             "dist/my-app/.nuxt",
+            "{projectRoot}/.output",
           ],
         },
         "serve": {

packages/nuxt/src/plugins/plugin.ts

@@ -233,7 +233,7 @@ function getOutputs(
   );
 
   return {
-    buildOutputs: [buildOutputPath],
+    buildOutputs: [buildOutputPath, '{projectRoot}/.output'],
   };
 }