feat: integrate $fetch with ohmyfetch

packages/nitro/src/index.ts

@@ -1,4 +1,5 @@
 import nuxt2 from './module/nuxt2'
+export * from './types'
 
 export default function () {
   const { nuxt } = this

packages/nitro/src/types.ts

@@ -0,0 +1,11 @@
+import type { $Fetch } from 'ohmyfetch'
+
+declare global {
+  const $fetch: $Fetch
+
+  namespace NodeJS {
+    interface Global {
+      $fetch: $Fetch
+    }
+  }
+}