fix(nuxt): add missing type for head in defineNuxtComponent (#25410)

packages/nuxt/src/app/types/augments.d.ts

@@ -1,3 +1,4 @@
+import type { UseHeadInput } from "@unhead/vue";
 import type { NuxtApp, useNuxtApp } from '../nuxt'
 
 interface NuxtStaticBuildFlags {
@@ -33,4 +34,11 @@ declare module 'vue' {
     _nuxtOnBeforeMountCbs: Function[]
     _nuxtIdIndex?: Record<string, number>
   }
+  interface ComponentCustomOptions {
+    /**
+     * Available exclusively for `defineNuxtComponent`.
+     * It will not be executed when using `defineComponent`.
+     */
+    head?(nuxtApp: NuxtApp): UseHeadInput
+  }
 }

test/fixtures/basic-types/types.ts

@@ -329,6 +329,25 @@ describe('head', () => {
       }
     })
   })
+  it('types head for defineNuxtComponent', () => {
+    defineNuxtComponent({
+      head(nuxtApp) {
+        expectTypeOf(nuxtApp).not.toBeAny()
+        return {
+          title: 'Site Title'
+        }
+      }
+    })
+
+    defineNuxtComponent({
+      // @ts-expect-error wrong return type for head function
+      head() {
+        return {
+          'test': true
+        }
+      }
+    })
+  })
 })
 
 describe('components', () => {