fix: show env status warning in survey tab + add alert on survey failure

- Add isEnvAlive check on mount via /api/simulation/env-status
- Show warning banner when simulation env is not running
- Add alert() on survey failure for visibility
- Add envNotRunning translation key for th/en/zh

frontend/src/components/Step5Interaction.vue

@@ -315,6 +315,10 @@
         <div v-if="activeTab === 'survey'" class="survey-container">
           <!-- Survey Setup -->
           <div class="survey-setup">
+            <!-- Env status warning -->
+            <div v-if="!isEnvAlive" class="survey-env-warning">
+              ⚠️ {{ $t('step5.envNotRunning') || 'Simulation environment is not running. Survey requires an active simulation environment.' }}
+            </div>
             <div class="setup-section">
               <div class="section-header">
                 <span class="section-title">{{ $t('step5.selectSurveyTarget') }}</span>
@@ -414,7 +418,7 @@
 import { ref, computed, watch, onMounted, onUnmounted, nextTick } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { chatWithReport, getReport, getAgentLog } from '../api/report'
-import { interviewAgents, getSimulationProfilesRealtime } from '../api/simulation'
+import { interviewAgents, getSimulationProfilesRealtime, getEnvStatus } from '../api/simulation'
 
 const { t } = useI18n()
 
@@ -445,9 +449,9 @@ const chatInputRef = ref(null)
 // Survey State
 const selectedAgents = ref(new Set())
 const surveyQuestion = ref('')
+const isEnvAlive = ref(false)
 const surveyResults = ref([])
 const isSurveying = ref(false)
-
 // Report Data
 const reportOutline = ref(null)
 const generatedSections = ref({})
@@ -782,6 +786,16 @@ const scrollToBottom = () => {
 }
 
 // Survey Methods
+const checkEnvStatus = async () => {
+  if (!props.simulationId) return
+  try {
+    const res = await getEnvStatus({ simulation_id: props.simulationId })
+    isEnvAlive.value = res.success && res.data?.running === true
+  } catch {
+    isEnvAlive.value = false
+  }
+}
+
 const toggleAgentSelection = (idx) => {
   const newSet = new Set(selectedAgents.value)
   if (newSet.has(idx)) {
@@ -945,6 +959,7 @@ onMounted(() => {
   addLog(t('log.step5Init'))
   loadReportData()
   loadProfiles()
+  checkEnvStatus()
   document.addEventListener('click', handleClickOutside)
 })
 
@@ -2155,6 +2170,18 @@ watch(() => props.simulationId, (newId) => {
 
 /* Survey Container */
 .survey-container {
+  /* env warning */
+}
+
+.survey-env-warning {
+  background: #FFF3CD;
+  color: #856404;
+  border: 1px solid #FFEAA7;
+  border-radius: 6px;
+  padding: 10px 14px;
+  margin-bottom: 12px;
+  font-size: 0.85rem;
+}
   flex: 1;
   display: flex;
   flex-direction: column;