feat: export core

Author: KeJunMao

src/core/index.ts

@@ -0,0 +1,4 @@
+export * from "./context"
+export * from "./directive"
+export * from "./directives"
+export * from "./unplugin"

src/index.ts

@@ -1,4 +1,2 @@
 export * from './types'
-export * from './core/directive'
-export { default } from './core/unplugin'
-export * from './core/directives'
+export * from './core'