Show round timer, players and jackpot in the dashboard

A card above the section menu polls GET /rounds/current every 15s and
ticks a mm:ss countdown to closes_at every second locally, showing
status (aperto/in chiusura/estrazione/pagamento), participant count
and jackpot in PLM. Refreshed immediately after placing a bet, and
timers are cleared on logout.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/static/index.html

@@ -198,6 +198,23 @@
     </div>
   </div>
 
+  <div class="card">
+    <div class="row-between">
+      <h2 id="round-title">Round —</h2>
+      <span class="mono" id="round-timer" style="font-size:1.1rem;font-weight:700">--:--</span>
+    </div>
+    <div class="row-between" style="margin-top:10px">
+      <div>
+        <div class="hint" style="margin-bottom:2px">Giocatori</div>
+        <span class="mono" id="round-players">—</span>
+      </div>
+      <div style="text-align:right">
+        <div class="hint" style="margin-bottom:2px">Jackpot</div>
+        <span class="mono" id="round-jackpot">—</span> <span class="balance-unit">PLM</span>
+      </div>
+    </div>
+  </div>
+
   <nav class="menu" aria-label="Sezioni">
     <button class="nav-item active" id="nav-deposit" onclick="switchPanel('deposit')">
       <svg class="icon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><rect x="2" y="7" width="20" height="14" rx="2"/><path d="M16 21V5a2 2 0 0 0-2-2H6a2 2 0 0 0-2 2v16"/></svg>
@@ -316,6 +333,39 @@ function switchPanel(name) {
   }
 }
 
+let roundCloseAt = null;
+let roundTimerInterval = null;
+let roundPollInterval = null;
+
+const ROUND_STATUS_LABELS = {
+  open: 'aperto',
+  closing: 'in chiusura',
+  drawing: 'estrazione in corso',
+  paying_out: 'pagamento in corso',
+};
+
+function updateRoundTimer() {
+  const el = document.getElementById('round-timer');
+  if (!roundCloseAt) { el.textContent = '--:--'; return; }
+  const totalSec = Math.max(0, Math.floor((roundCloseAt - new Date()) / 1000));
+  const mm = String(Math.floor(totalSec / 60)).padStart(2, '0');
+  const ss = String(totalSec % 60).padStart(2, '0');
+  el.textContent = mm + ':' + ss;
+}
+
+async function refreshRound() {
+  try {
+    const data = await call('GET', '/rounds/current');
+    document.getElementById('round-title').textContent = data.round_id
+      ? 'Round #' + data.round_id + ' — ' + (ROUND_STATUS_LABELS[data.status] || data.status)
+      : 'Nessun round attivo';
+    document.getElementById('round-players').textContent = data.participant_count;
+    document.getElementById('round-jackpot').textContent = data.jackpot_sats / SATS_PER_PLM;
+    roundCloseAt = data.closes_at ? new Date(data.closes_at) : null;
+    updateRoundTimer();
+  } catch (e) {}
+}
+
 function showDashboard() {
   document.getElementById('auth-section').classList.add('hidden');
   document.getElementById('dashboard-section').classList.remove('hidden');
@@ -323,6 +373,11 @@ function showDashboard() {
   document.getElementById('dash-address').textContent = address;
   document.getElementById('dash-qr').src = '/qr/' + encodeURIComponent(address);
   refreshMe();
+  refreshRound();
+  clearInterval(roundTimerInterval);
+  clearInterval(roundPollInterval);
+  roundTimerInterval = setInterval(updateRoundTimer, 1000);
+  roundPollInterval = setInterval(refreshRound, 15000);
 }
 
 function persistSession(data, u) {
@@ -367,6 +422,8 @@ async function login() {
 function logout() {
   localStorage.clear();
   token = username = address = null;
+  clearInterval(roundTimerInterval);
+  clearInterval(roundPollInterval);
   document.getElementById('dashboard-section').classList.add('hidden');
   document.getElementById('auth-section').classList.remove('hidden');
 }
@@ -403,6 +460,7 @@ async function placeBet() {
     }
   });
   refreshMe();
+  refreshRound();
 }
 
 async function withdraw() {