feat(cms): keyboard shortcuts — Ctrl+S save, Ctrl+P publish, ? help

- Ctrl/Cmd+S saves (native browser save dialog suppressed)
- Ctrl/Cmd+P publishes; Ctrl/Cmd+Shift+V opens the Versions panel
- '?' toggles a shortcuts overlay (Esc/click closes)
- plain typing in inputs never triggers actions (modifiers required;
  '?' only outside editing targets)
- jsdom regression tests run the real client script with dispatched
  KeyboardEvents; the client is evaluated once per suite because each
  eval would stack another keydown listener on the shared document

Closes MITHOME-75

scripts/cms-editor-client.js

@@ -329,3 +329,59 @@ render(DATA, document.getElementById('editor'));
 // Auto-dismiss toast
 const toast = document.querySelector('.toast');
  if (toast) setTimeout(() => toast.remove(), 3500);
+
+// ── Keyboard shortcuts ───────────────────────────────────────────────────────
+// Ctrl/Cmd+S save · Ctrl/Cmd+P publish · Ctrl/Cmd+Shift+V versions · ? help
+// Plain typing in inputs never triggers actions — the handler requires the
+// modifier key (or, for '?', a non-editing target).
+
+function showShortcutsOverlay() {
+  const existing = document.getElementById('shortcuts-overlay');
+  if (existing) { existing.remove(); return; }
+  const overlay = document.createElement('div');
+  overlay.id = 'shortcuts-overlay';
+  overlay.style.cssText = 'position:fixed;inset:0;background:rgba(15,17,23,.75);z-index:300;display:flex;align-items:center;justify-content:center;padding:24px;';
+  overlay.innerHTML = `
+    <div style="background:#1a2035;border:1px solid #2d3748;border-radius:14px;padding:28px 32px;max-width:420px;width:100%;font-size:14px;line-height:2;color:#e2e8f0;">
+      <h2 style="font-size:16px;color:#93c5fd;margin-bottom:12px;">⌨️ Gyorsbillentyűk</h2>
+      <div><kbd style="background:#0f1420;border:1px solid #2d3748;border-radius:5px;padding:2px 8px;font-family:monospace;">Ctrl/Cmd + S</kbd> — Mentés</div>
+      <div><kbd style="background:#0f1420;border:1px solid #2d3748;border-radius:5px;padding:2px 8px;font-family:monospace;">Ctrl/Cmd + P</kbd> — Publikálás</div>
+      <div><kbd style="background:#0f1420;border:1px solid #2d3748;border-radius:5px;padding:2px 8px;font-family:monospace;">Ctrl/Cmd + Shift + V</kbd> — Verziók</div>
+      <div><kbd style="background:#0f1420;border:1px solid #2d3748;border-radius:5px;padding:2px 8px;font-family:monospace;">?</kbd> — ez a súgó (Esc: bezárás)</div>
+    </div>`;
+  overlay.addEventListener('click', () => overlay.remove());
+  document.body.appendChild(overlay);
+}
+
+document.addEventListener('keydown', e => {
+  // Esc closes the shortcut overlay if open
+  if (e.key === 'Escape') {
+    const overlay = document.getElementById('shortcuts-overlay');
+    if (overlay) { overlay.remove(); e.preventDefault(); }
+    return;
+  }
+  const mod = e.ctrlKey || e.metaKey;
+  if (mod && !e.shiftKey && !e.altKey && (e.key === 's' || e.key === 'S')) {
+    e.preventDefault();
+    save();
+    return;
+  }
+  if (mod && !e.shiftKey && !e.altKey && (e.key === 'p' || e.key === 'P')) {
+    e.preventDefault();
+    publish();
+    return;
+  }
+  if (mod && e.shiftKey && (e.key === 'v' || e.key === 'V')) {
+    e.preventDefault();
+    window.open('/versions?file=' + encodeURIComponent(FILE), '_blank');
+    return;
+  }
+  if (!mod && !e.ctrlKey && !e.metaKey && !e.altKey && e.key === '?') {
+    const target = e.target;
+    const isEditing = target && (target.tagName === 'INPUT' || target.tagName === 'TEXTAREA' || target.isContentEditable);
+    if (!isEditing) {
+      e.preventDefault();
+      showShortcutsOverlay();
+    }
+  }
+});