Redesign: alerts above fold, fix nav, globalise suppress modal

- Dashboard: reorder sections so Active Alerts appear immediately below
  stat cards rather than after 200+ lines of topology — primary content
  is now above the fold on all screen sizes
- Network Hosts section gains a collapse toggle (persisted to localStorage)
  so the topology diagram can be hidden when not needed
- Admin nav corrected: admin now gets a direct Suppressions link;
  non-admin no longer sees the page at all (it was always admin-only)
- Suppress modal moved from index.html into base.html so [S] keyboard
  shortcut works on every page, not just the dashboard; form listeners
  wired in app.js accordingly
- Settings modal KV grid: replaced lt-kv-row/lt-kv-label/lt-kv-value
  (light-mode only) with lt-kv-key/lt-kv-val (dark-mode defined)
- style.css: add lt-btn-secondary dark-mode definition, lt-cmd-hint-btn
  class for ⌘K button, topology collapse styles; remove dead .g-page-header,
  .g-page-title, .empty-state classes; strip redundant inline styles

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

static/app.js

@@ -334,6 +334,10 @@ async function submitSuppress(e) {
   }
 }
 
+// ── Suppress form – wired here so the modal works from any page ──────
+document.getElementById('suppress-form')?.addEventListener('submit', submitSuppress);
+document.getElementById('sup-type')?.addEventListener('change', updateSuppressForm);
+
 // ── Global click delegation ───────────────────────────────────────────
 document.addEventListener('click', e => {
   // Refresh button