feat: Implement segment update and regeneration features in Audiobook API and frontend

qwen3-tts-frontend/src/locales/en-US/audiobook.json

@@ -115,7 +115,16 @@
 
     "segments": {
       "errorBadge": "Error",
-      "unknownCharacter": "?"
+      "unknownCharacter": "?",
+      "edit": "Edit",
+      "save": "Save",
+      "cancel": "Cancel",
+      "regenerate": "Regenerate",
+      "regenerating": "Generating...",
+      "savedSuccess": "Segment saved",
+      "emotion": "Emotion",
+      "noEmotion": "No emotion",
+      "intensity": "Intensity"
     },
 
     "sequential": {

qwen3-tts-frontend/src/locales/ja-JP/audiobook.json

@@ -114,7 +114,16 @@
 
     "segments": {
       "errorBadge": "エラー",
-      "unknownCharacter": "?"
+      "unknownCharacter": "?",
+      "edit": "編集",
+      "save": "保存",
+      "cancel": "キャンセル",
+      "regenerate": "再生成",
+      "regenerating": "生成中...",
+      "savedSuccess": "セグメントを保存しました",
+      "emotion": "感情",
+      "noEmotion": "感情なし",
+      "intensity": "強度"
     },
 
     "sequential": {

qwen3-tts-frontend/src/locales/ko-KR/audiobook.json

@@ -114,7 +114,16 @@
 
     "segments": {
       "errorBadge": "오류",
-      "unknownCharacter": "?"
+      "unknownCharacter": "?",
+      "edit": "편집",
+      "save": "저장",
+      "cancel": "취소",
+      "regenerate": "재생성",
+      "regenerating": "생성 중...",
+      "savedSuccess": "세그먼트가 저장되었습니다",
+      "emotion": "감정",
+      "noEmotion": "감정 없음",
+      "intensity": "강도"
     },
 
     "sequential": {

qwen3-tts-frontend/src/locales/zh-CN/audiobook.json

@@ -118,7 +118,16 @@
 
     "segments": {
       "errorBadge": "出错",
-      "unknownCharacter": "?"
+      "unknownCharacter": "?",
+      "edit": "编辑",
+      "save": "保存",
+      "cancel": "取消",
+      "regenerate": "重新生成",
+      "regenerating": "生成中...",
+      "savedSuccess": "片段已保存",
+      "emotion": "情绪",
+      "noEmotion": "无情绪",
+      "intensity": "强度"
     },
 
     "sequential": {

qwen3-tts-frontend/src/locales/zh-TW/audiobook.json

@@ -114,7 +114,16 @@
 
     "segments": {
       "errorBadge": "出錯",
-      "unknownCharacter": "?"
+      "unknownCharacter": "?",
+      "edit": "編輯",
+      "save": "儲存",
+      "cancel": "取消",
+      "regenerate": "重新生成",
+      "regenerating": "生成中...",
+      "savedSuccess": "片段已儲存",
+      "emotion": "情緒",
+      "noEmotion": "無情緒",
+      "intensity": "強度"
     },
 
     "sequential": {