fix: trace debug — show Stranger_NNN for unnamed traces instead of unknown

portal/src/components/TranslatableText.vue

@@ -30,6 +30,7 @@
       </div>
       {{ translatedText }}
     </div>
+    <div v-if="errorMsg" class="mt-2 text-xs text-red-400">{{ errorMsg }}</div>
   </div>
 </template>
 
@@ -45,16 +46,19 @@ const targetLang = ref('zh-TW')
 const translatedText = ref('')
 const loading = ref(false)
 const showTranslation = ref(false)
+const errorMsg = ref('')
 
 const translate = async () => {
   if (!props.text.trim()) return
   
   loading.value = true
+  errorMsg.value = ''
   try {
     translatedText.value = await translateText(props.text, targetLang.value)
     showTranslation.value = true
   } catch (error) {
-    console.error('Translation failed:', error)
+    errorMsg.value = '翻譯失敗: ' + (error as any)?.message || String(error)
+    showTranslation.value = false
   } finally {
     loading.value = false
   }