[verified] add event-study readiness gate

frontend/src/App.vue

@@ -5,6 +5,7 @@ const summary = ref(null)
 const observations = ref(null)
 const signalData = ref(null)
 const ledger = ref({ entries: [] })
+const backtest = ref(null)
 const loading = ref(true)
 const error = ref('')
 const notice = ref('')
@@ -47,22 +48,33 @@ async function fetchJson(url, options) {
   return response.json()
 }
 
+async function fetchBacktestReadiness() {
+  const response = await fetch('/api/v1/backtest/tourism?min_events=12')
+  const body = await response.json().catch(() => ({}))
+  if (![200, 409].includes(response.status)) {
+    throw new Error(body.error || `Request failed: ${response.status}`)
+  }
+  return body
+}
+
 async function loadDashboard() {
   loading.value = true
   error.value = ''
   try {
-    const [summaryBody, observationBody, signalBody, ledgerBody, sessionBody] = await Promise.all([
+    const [summaryBody, observationBody, signalBody, ledgerBody, sessionBody, backtestBody] = await Promise.all([
       fetchJson('/api/v1/dashboard/summary'),
       fetchJson('/api/v1/factors/tourism/observations'),
       fetchJson('/api/v1/signals'),
       fetchJson('/api/v1/paper/ledger'),
       fetchJson('/api/v1/auth/paper', { credentials: 'include' }),
+      fetchBacktestReadiness(),
     ])
     summary.value = summaryBody
     observations.value = observationBody
     signalData.value = signalBody
     ledger.value = ledgerBody
     paperAuthenticated.value = Boolean(sessionBody.authenticated)
+    backtest.value = backtestBody
   } catch (caught) {
     error.value = caught.message
   } finally {
@@ -205,6 +217,11 @@ onMounted(loadDashboard)
             <div class="kpi-value quality-value">{{ summary.data_health.status }}</div>
             <div class="kpi-foot">Vintage {{ summary.data_health.vintage_id }}</div>
           </article>
+          <article class="kpi-card">
+            <div class="kpi-label">Backtest gate</div>
+            <div class="kpi-value quality-value">{{ backtest?.status || '—' }}</div>
+            <div class="kpi-foot">{{ backtest?.available_events || 0 }} / {{ backtest?.required_events || 0 }} vintages</div>
+          </article>
         </section>
 
         <section class="hero-grid" id="factors">