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

test/types/danmuku-root.ts

@@ -0,0 +1,22 @@
+import type { Option, Result } from 'artplayer-plugin-danmuku'
+import danmuku from 'artplayer-plugin-danmuku'
+import legacy from 'artplayer-plugin-danmuku/legacy'
+
+const legacyFactory: typeof danmuku = legacy
+const rootFactory: typeof legacy = danmuku
+const option: Option = { danmuku: [], points: [{ time: 1, value: 2 }] }
+danmuku(option)
+legacy(option)
+declare const result: Result
+const synchronous: Result = result.emit({ text: 'historical declaration' })
+void [legacyFactory, rootFactory, synchronous]
+
+// @ts-expect-error The published root requires its option argument.
+danmuku()
+// @ts-expect-error The published root requires danmuku in Option.
+danmuku({})
+// @ts-expect-error Preserve historical object points at the root.
+danmuku({ danmuku: [], points: [[1, 2]] })
+// @ts-expect-error Root emit keeps its published synchronous Result shape.
+const asynchronous: Promise<Result> = result.emit({ text: 'old emit' })
+void asynchronous