eat: implement Holesail-Browser enhancement plan

- Add unit tests (hostname-validator, TLDs, payload-schemas) and integration tests for message handler registry
- Refactor native host message router into handler registry (handlers/state, tunnels, ssh, rdp, backup, ca, connections)
- Add ESLint config and npm test + lint steps in CI
- Dashboard: visibility-based refresh pause, configurable refresh interval (2s/5s/10s/paused)
- Accessibility: ARIA on nav and modals, focus trap and restore, prefers-reduced-motion
- Empty states: primary action buttons for virtual hosts, servers, service tunnels
- Native host rate limiting for backup and CA operations; update SECURITY.md
- CONTRIBUTING: "Adding a new dashboard page", dev workflow; add npm run dev script

extension/dashboard/events.js

@@ -35,10 +35,19 @@ function setupEvents() {
     });
   });
 
-  // Mark settings dirty when any number input inside the settings page changes
+  // Mark settings dirty when any number input or select inside the settings page changes
   document.querySelectorAll('#page-settings input[type="number"]').forEach(input => {
     input.addEventListener('input', _markSettingsDirty);
   });
+  document.querySelectorAll('#page-settings select').forEach(sel => {
+    sel.addEventListener('change', _markSettingsDirty);
+  });
+
+  // Empty-state primary buttons: open the corresponding add modal
+  document.addEventListener('click', (e) => {
+    const btn = e.target.closest('[data-open-modal]');
+    if (btn && btn.dataset.openModal) openModal(btn.dataset.openModal);
+  });
 
   // Save settings
   $('btnSaveSettings')?.addEventListener('click', saveSettings);
@@ -52,6 +61,8 @@ function setupEvents() {
         if (response && response.settings) settings = { ...SETTINGS_DEFAULTS, ...response.settings };
         _clearSettingsDirty();
         updateSettingsUI();
+        if (typeof window._restartRefreshInterval === 'function') window._restartRefreshInterval();
+        if (typeof window._restartPingInterval === 'function') window._restartPingInterval();
         showToast('Settings reset to defaults', 'success');
       }
     );