docs: migrate to nuxt compatibility 4

docs/app/layouts/default.vue

@@ -0,0 +1,5 @@
+<template>
+  <div>
+    <slot />
+  </div>
+</template>

docs/app/layouts/docs.vue

@@ -0,0 +1,25 @@
+<template>
+  <UMain>
+    <UContainer>
+      <UPage>
+        <template #left>
+          <UPageAside>
+            <!-- <BranchSelect /> -->
+
+            <UContentNavigation :navigation="navigation" />
+          </UPageAside>
+        </template>
+
+        <slot />
+      </UPage>
+    </UContainer>
+  </UMain>
+</template>
+
+<script setup lang="ts">
+import type { NavItem } from '@nuxt/content/dist/runtime/types'
+
+const nav = inject<Ref<NavItem[]>>('navigation')
+
+const navigation = computed(() => nav.value.filter(item => !item._path.startsWith('/pro')))
+</script>