feat: add Hermes integration panel to Settings → Integrations

Server-side:
- New hermes-integration module (runtime.js + routes.js + tests)
  exposing GET /api/openchamber/hermes/status
- Reports availability of agent-activity, session-steer, and plan-gate
  runtimes plus plan-gate default config
- Wired into feature-routes-runtime.js alongside existing integrations

UI:
- New HermesIntegration.tsx collapsible panel in Integrations page
- Connection status indicator (green/red dot) with 30s polling
- Plan gate default toggle (persists via updateDesktopSettings +
  recordDeferredOpenCodeRestart)
- Read-only status rows for activity stream, steer channel, plan gate
- Server version and uptime display

Settings:
- hermesPlanGateDefault field in settings registry and useUIStore
- Search index entry with keywords: hermes, agent, integration, etc.
- i18n keys for all 12 locales (English text as fallback)

Verification:
- Server tests: 7/7 passed (runtime + routes)
- UI tests: 4/4 passed (HermesIntegration.test.tsx)
- Typecheck: clean (no new errors)
- oxlint: clean on all new/modified files

packages/web/server/lib/hermes-integration/routes.test.js

@@ -0,0 +1,49 @@
+import express from 'express';
+import request from 'supertest';
+import { describe, expect, it, vi } from 'vitest';
+
+import { registerHermesIntegrationRoutes } from './routes.js';
+
+const createApp = (getStatus) => {
+  const app = express();
+  registerHermesIntegrationRoutes(app, { getStatus });
+  return app;
+};
+
+describe('Hermes integration route', () => {
+  it('returns status JSON from the runtime', async () => {
+    const getStatus = vi.fn(async () => ({
+      ok: true,
+      server: { version: '1.23.0', uptimeMs: 5000 },
+      integrations: {
+        agentActivity: { available: true },
+        steer: { available: true },
+        planGate: { available: true },
+      },
+      config: {
+        planGateDefault: false,
+        activityRateLimitMs: 2000,
+      },
+    }));
+    const response = await request(createApp(getStatus))
+      .get('/api/openchamber/hermes/status')
+      .expect(200);
+
+    expect(response.body.ok).toBe(true);
+    expect(response.body.server.version).toBe('1.23.0');
+    expect(response.body.integrations.agentActivity.available).toBe(true);
+    expect(getStatus).toHaveBeenCalledOnce();
+  });
+
+  it('returns 500 on runtime failure', async () => {
+    const getStatus = vi.fn(async () => {
+      throw new Error('runtime exploded');
+    });
+    const response = await request(createApp(getStatus))
+      .get('/api/openchamber/hermes/status')
+      .expect(500);
+
+    expect(response.body.ok).toBe(false);
+    expect(response.body.error).toBe('runtime exploded');
+  });
+});