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/index.js

@@ -0,0 +1,38 @@
+/**
+ * Aggregates all message handlers into a single type -> handle map.
+ * Each handler module exports register(deps) and returns an array of { type, handle }.
+ * deps must include all manager refs plus debugLog and log (for handlers that log).
+ */
+
+const stateHandlers = require('./state.js');
+const connectionsHandlers = require('./connections.js');
+const tunnelsHandlers = require('./tunnels.js');
+const caHandlers = require('./ca.js');
+const sshHandlers = require('./ssh.js');
+const rdpHandlers = require('./rdp.js');
+const backupHandlers = require('./backup.js');
+
+/**
+ * Build the handler registry. Pass the same deps that message-router has.
+ * @returns {Map<string, Function>} type -> async (payload, reply) => void
+ */
+function buildHandlers(deps) {
+  const entries = [
+    ...stateHandlers.register(deps),
+    ...connectionsHandlers.register(deps),
+    ...tunnelsHandlers.register(deps),
+    ...caHandlers.register(deps),
+    ...sshHandlers.register(deps),
+    ...rdpHandlers.register(deps),
+    ...backupHandlers.register(deps)
+  ];
+
+  const map = new Map();
+  for (const { type, handle } of entries) {
+    if (map.has(type)) throw new Error(`Duplicate handler for type: ${type}`);
+    map.set(type, handle);
+  }
+  return map;
+}
+
+module.exports = { buildHandlers };