新增播放速率调整功能

src/renderer/store/player/playbackRate.ts

@@ -0,0 +1,8 @@
+import { ref } from '@common/utils/vueTools'
+
+
+export const playbackRate = ref(1)
+
+export const setplaybackRate = (num: number) => {
+  playbackRate.value = num
+}