Wire up the SSE push channel in both frontend dashboards

app/static/index.html: opens an EventSource against /rounds/stream (no auth
needed, see the previous commit) alongside the existing polling loops. On an
"update" notification, immediately re-runs the same refreshes polling would
eventually do (refreshRound/refreshMe/checkLastRoundResult when logged in,
refreshChainStatusOnly when logged out). Also reacts to the browser's "open"
event, which fires on the initial connection and on every automatic
reconnect — this re-syncs right away instead of leaving the page on stale
state until the next event or poll tick, which matters most right after a
dropped connection comes back.

app/static/admin.html: same channel, refreshing the chain-status bar and
whichever admin section is currently open (Utenti/Round/Transazioni
pendenti/Audit log) instead of requiring a manual tab switch to see new data.

Polling intervals are untouched in both pages — this is purely additive, so
a blocked/dropped SSE connection just degrades to the pre-existing behavior.

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

app/static/admin.html

@@ -241,14 +241,16 @@ function stopChainStatusPolling() {
 }
 
 const VIEWS = ['parametri', 'utenti', 'round', 'pending', 'audit'];
+const VIEW_LOADERS = { utenti: loadUsers, round: loadRounds, pending: loadPending, audit: loadAuditLog };
+let currentAdminView = 'parametri';
 
 function switchView(name) {
+  currentAdminView = name;
   for (const key of VIEWS) {
     document.getElementById('nav-' + key).classList.toggle('active', key === name);
     document.getElementById('view-' + key).classList.toggle('active', key === name);
   }
-  const loaders = { utenti: loadUsers, round: loadRounds, pending: loadPending, audit: loadAuditLog };
-  if (loaders[name]) loaders[name]();
+  if (VIEW_LOADERS[name]) VIEW_LOADERS[name]();
 }
 
 function showDashboard() {
@@ -521,6 +523,31 @@ window.addEventListener('pageshow', (event) => {
   if (event.persisted) initAuthState();
 });
 
+// Same server-push channel as app/static/index.html (see app/rounds/events.py):
+// a content-free "something changed" ping. Here it refreshes the chain-status
+// bar immediately, and reloads whichever admin section is currently open
+// (Utenti/Round/Transazioni pendenti/Audit log) so it doesn't need a manual
+// switch-away-and-back to pick up a new row. Polling stays in place as a
+// fallback if this connection is ever blocked or drops.
+let adminEventSource = null;
+
+function onAdminServerEvent() {
+  if (!adminToken) return;
+  refreshChainStatus();
+  if (VIEW_LOADERS[currentAdminView]) VIEW_LOADERS[currentAdminView]();
+}
+
+function connectAdminEvents() {
+  if (adminEventSource) return;
+  adminEventSource = new EventSource('/rounds/stream');
+  adminEventSource.addEventListener('update', onAdminServerEvent);
+  // Fires on the initial connection AND every successful auto-reconnect —
+  // re-syncs immediately instead of waiting for the next event or poll tick
+  // to notice whatever changed while this connection was down.
+  adminEventSource.addEventListener('open', onAdminServerEvent);
+}
+
+connectAdminEvents();
 initAuthState();
 </script>