feat(vapor): add vapor flag for createVaporApp (#13360)

packages/runtime-core/src/apiCreateApp.ts

@@ -35,6 +35,7 @@ import { ErrorCodes, callWithAsyncErrorHandling } from './errorHandling'
 import type { DefineComponent } from './apiDefineComponent'
 
 export interface App<HostElement = any> {
+  vapor?: boolean
   version: string
   config: AppConfig
 

packages/runtime-vapor/src/apiCreateApp.ts

@@ -100,6 +100,7 @@ function postPrepareApp(app: App) {
     )
   }
 
+  app.vapor = true
   const mount = app.mount
   app.mount = (container, ...args: any[]) => {
     container = normalizeContainer(container) as ParentNode