refactor(danmuku): [PKG-DANMUKU-06] migrate runtime and preserve public types

refactor/fixtures/implementation/danmuku.ts

@@ -0,0 +1,6 @@
+import type { RuntimeFactory } from 'artplayer-plugin-danmuku/runtime'
+import factory from '../../../packages/artplayer-plugin-danmuku/src'
+
+// Compile with the package configuration: the implementation imports Worker assets.
+const implementation: RuntimeFactory = factory
+export { implementation }