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

native-host/host/handlers/connections.js

@@ -0,0 +1,32 @@
+/**
+ * Handlers for SSH and RDP connection list get/set.
+ * Context: holesailManager, debugLog
+ */
+
+function register(deps) {
+  const { holesailManager, debugLog } = deps;
+  return [
+    { type: 'getSshConnections', handle: async (payload, reply) => reply({ ok: true, sshConnections: holesailManager.getSshConnections() }) },
+    {
+      type: 'setSshConnections',
+      handle: async (payload, reply) => {
+        const list = Array.isArray(payload.connections) ? payload.connections : [];
+        holesailManager.setSshConnections(list);
+        debugLog('setSshConnections: count=', list.length);
+        reply({ ok: true });
+      }
+    },
+    { type: 'getRdpConnections', handle: async (payload, reply) => reply({ ok: true, rdpConnections: holesailManager.getRdpConnections() }) },
+    {
+      type: 'setRdpConnections',
+      handle: async (payload, reply) => {
+        const list = Array.isArray(payload.connections) ? payload.connections : [];
+        holesailManager.setRdpConnections(list);
+        debugLog('setRdpConnections: count=', list.length);
+        reply({ ok: true });
+      }
+    }
+  ];
+}
+
+module.exports = { register };