refactor(core): [CORE-23] complete keyboard controls and focus lifecycle

packages/artplayer/dist/playback.ts

@@ -0,0 +1,6 @@
+/** Accurate playback method view; assign an existing player without a runtime wrapper. */
+export interface PlaybackControls {
+  play: () => Promise<void>
+  pause: () => void
+  toggle: () => Promise<void> | void
+}