feat(kling): add validation error display in timeline panel and update UI components

- Remove unused audio base64 reference and error message in VoiceSelector
- Rename CSS class from 'result-banner' to 'result-inline' and update button styling
- Pass validationError prop from GenerateStep to TimelinePanel
- Add validation error display in TimelinePanel with error state styling
- Update conditional rendering to show either validation error or duration diff
- Add CloseCircleOutlined icon for error status display

frontend/app/web-gold/src/components/VoiceSelector.vue

@@ -103,7 +103,6 @@ const playerContainer = ref(null)
 const audioUrl = ref('')
 const currentVoiceName = ref('')
 const isPlayerInitializing = ref(false)
-const currentAudioBase64 = ref('')  // 保存当前音频的 base64 数据
 
 // 默认封面图片（音频波形图标）
 const defaultCover = `data:image/svg+xml;base64,${btoa(`
@@ -208,7 +207,6 @@ const handlePlayVoiceSample = (voice) => {
     (data) => {
       const url = data.audioUrl || data.objectUrl
       if (!url) return
-      currentAudioBase64.value = data.audioBase64 || ''
       initPlayer(url)
     },
     undefined, // 错误静默处理
@@ -259,7 +257,6 @@ const initPlayer = (url) => {
 
       player.on('error', (e) => {
         console.error('APlayer 播放错误:', e)
-        message.error('音频播放失败，请重试')
       })
 
       player.on('canplay', () => {