fix: sub module types

Author: antfu

nuxt.d.ts

@@ -1,2 +1,3 @@
 import './global'
 export * from './dist/nuxt'
+export { default } from './dist/nuxt'

rollup-plugin.d.ts

@@ -0,0 +1,3 @@
+import './global'
+export * from './dist/rollup-plugin'
+export { default } from './dist/rollup-plugin'

vite-plugin.d.ts

@@ -1,2 +1,3 @@
 import './global'
 export * from './dist/vite-plugin'
+export { default } from './dist/vite-plugin'

webpack-plugin.d.ts

@@ -1,2 +1,3 @@
 import './global'
 export * from './dist/webpack-plugin'
+export { default } from './dist/webpack-plugin'