refactor: update export syntax to default for multiple plugins and adjust package.json formatting

packages/artplayer-plugin-auto-thumbnail/types/artplayer-plugin-auto-thumbnail.d.ts

@@ -1,8 +1,5 @@
 import type Artplayer from 'artplayer'
 
-export = artplayerPluginAutoThumbnail
-export as namespace artplayerPluginAutoThumbnail;
-
 interface Option {
   url?: string
   width?: number
@@ -15,3 +12,5 @@ interface Result {
 }
 
 declare const artplayerPluginAutoThumbnail: (option: Option) => (art: Artplayer) => Result
+
+export default artplayerPluginAutoThumbnail