Add stat cards, lt-frame alert queue, and timeline for resolved alerts

- Four lt-stat-card widgets (Critical, Warning, Hosts, Resolved 24h)
  below the status bar; Critical card pulses red when count > 0
- Clicking Critical or Warning card filters the events table by severity
- Events table wrapped in lt-frame with ASCII corner ornaments and
  lt-section-header; filter bar moved to lt-toolbar with lt-search icon
- Recently Resolved table replaced with lt-timeline component
- updateStatusBar() and updateHostGrid() keep stat card values live

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

static/app.js

@@ -89,6 +89,14 @@ function updateStatusBar(summary, lastCheck, daemonOk) {
     alertBadge.style.display = total ? '' : 'none';
   }
 
+  // Update stat cards
+  const scCrit = document.getElementById('stat-critical-val');
+  const scWarn = document.getElementById('stat-warning-val');
+  if (scCrit) scCrit.textContent = critCount;
+  if (scWarn) scWarn.textContent = warnCount;
+  const statCritCard = document.getElementById('stat-critical');
+  if (statCritCard) statCritCard.classList.toggle('lt-stat-card--alert', critCount > 0);
+
   // Stale data banner: warn if last_check is older than 15 minutes
   let staleBanner = document.getElementById('stale-banner');
   if (lastCheck) {
@@ -112,6 +120,9 @@ function updateStatusBar(summary, lastCheck, daemonOk) {
 }
 
 function updateHostGrid(hosts) {
+  const scHosts = document.getElementById('stat-hosts-val');
+  if (scHosts) scHosts.textContent = Object.keys(hosts).length;
+
   for (const [name, host] of Object.entries(hosts)) {
     const card = document.querySelector(`.host-card[data-host="${CSS.escape(name)}"]`);
     if (!card) continue;

static/style.css

@@ -995,6 +995,17 @@
 .diag-pulse-link a { color: var(--cyan); }
 .diag-pulse-link a:hover { text-shadow: var(--glow-cyan); }
 
+/* ── Stat card alert variant (pulsing border when critical > 0) ─── */
+.lt-stat-card--alert {
+  border-color: var(--red) !important;
+  box-shadow: 0 0 8px rgba(255,45,85,.25) !important;
+  animation: topo-pulse-down 2s ease-in-out infinite;
+}
+.lt-stat-card--alert::before { background: var(--red); box-shadow: var(--glow-red); }
+
+/* ── lt-frame inside g-section: no extra bottom margin ────────────── */
+.g-section > .lt-frame { margin-bottom: 0; }
+
 /* ── Responsive ───────────────────────────────────────────────────── */
 @media (max-width: 768px) {
   .host-grid         { grid-template-columns: 1fr; }