add chinese subtitles

ios/OralTrainer/Views/TrainingView.swift

@@ -4,6 +4,8 @@ struct TrainingView: View {
     @ObservedObject var controller: PlayerController
     @ObservedObject var catalogVM: CatalogViewModel
     @Binding var continuousPlayback: Bool
+    @Binding var showChineseSubtitles: Bool
+    var chineseSubtitlePlaceholder: String = "正在翻译中文字幕…"
     let onFullscreen: () -> Void
 
     var body: some View {
@@ -14,6 +16,8 @@ struct TrainingView: View {
                     showsContinuousToggle: true,
                     continuousPlayback: $continuousPlayback,
                     showsLessonTitle: false,
+                    showChineseSubtitles: $showChineseSubtitles,
+                    chineseSubtitlePlaceholder: chineseSubtitlePlaceholder,
                     onFullscreen: onFullscreen
                 )
                 CatalogView(vm: catalogVM)
@@ -28,5 +32,8 @@ struct TrainingView: View {
                     : "已关闭连续播放，将循环播放当前句子"
             )
         }
+        .onChange(of: showChineseSubtitles) { enabled in
+            controller.showTransientMessage(enabled ? "已开启中文字幕" : "已关闭中文字幕")
+        }
     }
 }