Go-live gate: refuse unsafe live trading

Setting MODE=live alone no longer starts trading. check_live_ready requires an
active risk limit, MAX_POSITION_PCT < 1.0, LIVE_CONFIRMATION exactly
"I UNDERSTAND THE RISK", a minimum balance, and exchange credentials. Enforced
in Runtime.start_many (both start paths) and surfaced at GET /api/live-check;
the dashboard shows a banner and blocks the start buttons. Adds tests.

frontend/src/App.vue

@@ -33,6 +33,7 @@ const strategies = ref([])
 const strategiesLoading = ref(true)
 const presets = ref([])
 const multiStatus = ref({ running: false, strategies: [], total_pnl: 0, equity: 0 })
+const liveCheck = ref({ ok: true, mode: 'paper', blockers: [] })
 const positions = ref([])
 const orders = ref([])
 const events = ref([])
@@ -97,6 +98,13 @@ async function handleDeletePreset(id) {
 }
 
 async function handleStart(payload) {
+  if (liveCheck.value.mode === 'live' && !liveCheck.value.ok) {
+    status.value = {
+      ...status.value,
+      error: 'Live trading blocked: ' + liveCheck.value.blockers.join('; '),
+    }
+    return
+  }
   busy.value = true
   try {
     status.value = await api.startBot(payload)
@@ -112,7 +120,18 @@ async function refreshMulti() {
   multiStatus.value = await api.getMultiStatus()
 }
 
+async function refreshLiveCheck() {
+  liveCheck.value = await api.getLiveCheck()
+}
+
 async function handleStartMany(payload) {
+  if (liveCheck.value.mode === 'live' && !liveCheck.value.ok) {
+    status.value = {
+      ...status.value,
+      error: 'Live trading blocked: ' + liveCheck.value.blockers.join('; '),
+    }
+    return
+  }
   busy.value = true
   try {
     multiStatus.value = await api.startMany(payload)
@@ -249,7 +268,8 @@ onMounted(() => {
   statusTimer = setInterval(
     () => {
       api.getStatus().then((s) => (status.value = s)).catch(() => {})
-      refreshMulti().catch(() => {})
+  refreshMulti().catch(() => {})
+  refreshLiveCheck().catch(() => {})
     },
     3000,
   )
@@ -307,6 +327,16 @@ onUnmounted(() => {
       flattened. Restart the bot to resume (limits reset).
     </div>
 
+    <div
+      v-if="liveCheck.mode === 'live' && !liveCheck.ok"
+      class="rounded-lg border border-amber-500 bg-amber-500/15 p-3 text-sm text-amber-100"
+    >
+      <p class="font-semibold">Live trading is blocked by the go-live checks:</p>
+      <ul class="mt-1 list-disc pl-5">
+        <li v-for="(b, i) in liveCheck.blockers" :key="i">{{ b }}</li>
+      </ul>
+    </div>
+
     <div v-if="status.error" class="rounded-lg border border-rose-500/40 bg-rose-500/10 p-3 text-sm text-rose-200">
       {{ status.error }}
     </div>