support Theme.enhanceApp

lib/app/index.js

@@ -84,6 +84,14 @@ export function createApp() {
     }
   })
 
+  if (Theme.enhanceApp) {
+    Theme.enhanceApp({
+      app,
+      router,
+      siteData: useSiteData()
+    })
+  }
+
   return { app, router }
 }
 

lib/theme-default/index.js

@@ -1,9 +1,16 @@
 import Layout from './Layout.vue'
 
 /**
+ * @typedef {{
+ *   app: import('vue').App
+ *   router: import('../app/router').Router
+ *   siteData: import('vue').Ref<object>
+ * }} EnhanceAppContext
+ *
  * @type {{
  *   Layout: import('vue').ComponentOptions
  *   NotFound?: import('vue').ComponentOptions
+ *   enhanceApp?: (ctx: EnhanceAppContext) => void
  * }}
  */
 const Theme = {