add chinese subtitles

ios/OralTrainer/Models/TrainingModels.swift

@@ -7,6 +7,7 @@ struct SentenceBoundary: Identifiable, Equatable, Decodable {
     let text: String?
     let language: String?
     let referenceSpeechDurationMs: Int64?
+    let zhText: String?
 
     var id: Int { index }
 
@@ -15,6 +16,48 @@ struct SentenceBoundary: Identifiable, Equatable, Decodable {
         case startMs = "start_ms"
         case endMs = "end_ms"
         case referenceSpeechDurationMs = "reference_speech_duration_ms"
+        case zhText = "zh_text"
+    }
+
+    init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        index = try container.decode(Int.self, forKey: .index)
+        startMs = try container.decode(Int64.self, forKey: .startMs)
+        endMs = try container.decode(Int64.self, forKey: .endMs)
+        text = try container.decodeIfPresent(String.self, forKey: .text)
+        language = try container.decodeIfPresent(String.self, forKey: .language)
+        referenceSpeechDurationMs = try container.decodeIfPresent(Int64.self, forKey: .referenceSpeechDurationMs)
+        zhText = try container.decodeIfPresent(String.self, forKey: .zhText)
+    }
+
+    init(
+        index: Int,
+        startMs: Int64,
+        endMs: Int64,
+        text: String?,
+        language: String?,
+        referenceSpeechDurationMs: Int64?,
+        zhText: String? = nil
+    ) {
+        self.index = index
+        self.startMs = startMs
+        self.endMs = endMs
+        self.text = text
+        self.language = language
+        self.referenceSpeechDurationMs = referenceSpeechDurationMs
+        self.zhText = zhText
+    }
+
+    func withZhText(_ zhText: String?) -> SentenceBoundary {
+        SentenceBoundary(
+            index: index,
+            startMs: startMs,
+            endMs: endMs,
+            text: text,
+            language: language,
+            referenceSpeechDurationMs: referenceSpeechDurationMs,
+            zhText: zhText
+        )
     }
 }