feat: push selected events to a phone over ntfy

Adds a Notifications tab to Settings so an operator can pick which events
reach their phone, published to a single self-hosted ntfy topic.

The notifier subscribes to the realtime event hub the dashboard already
consumes, so every notifiable event keeps exactly one publisher. Inbound
media had no event, so `media.received` is added and published from the
existing durable `gotImage` gate in the chat service — one notification
per conversation, never repeated when the room re-syncs. It feeds the
in-app notification bell as well.

- Best-effort delivery: a rejecting or unreachable ntfy server is logged
  and never propagated into the path that produced the event.
- Events buffered before the notifier attaches are skipped, so a restart
  cannot replay a backlog to somebody's phone.
- Settings are applied field by field onto the live config object, so a
  save takes effect without a restart.
- The access token is environment-owned (NTFY_AUTH_TOKEN) like the other
  secrets: stripped before the settings record is written, never returned
  by the API, which reports only `hasAuthToken`.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/config-persistence.test.ts

@@ -44,6 +44,7 @@ describe('ConfigStore', () => {
     config.web.authToken = 'also-secret';
     config.web.agentReadToken = 'read-agent-secret';
     config.web.agentControlToken = 'control-agent-secret';
+    config.pushNotifications.authToken = 'ntfy-secret';
     store.save(config);
 
     const row = db.prepare('SELECT config_json FROM app_config WHERE id = 1').get() as { config_json: string };
@@ -51,9 +52,31 @@ describe('ConfigStore', () => {
     expect(row.config_json).not.toContain('also-secret');
     expect(row.config_json).not.toContain('read-agent-secret');
     expect(row.config_json).not.toContain('control-agent-secret');
+    expect(row.config_json).not.toContain('ntfy-secret');
     expect(JSON.parse(row.config_json)).not.toHaveProperty('database');
   });
 
+  it('takes the ntfy access token from the environment on every load', () => {
+    const config = getTestConfig();
+    config.pushNotifications.topic = 'redditbot-7f3a9c21';
+    config.pushNotifications.authToken = 'saved-token-must-be-ignored';
+    store.save(config);
+
+    const withToken = store.load({
+      OPENROUTER_API_KEY: 'environment-key',
+      WEB_DASHBOARD_TOKEN: 'environment-dashboard-token',
+      NTFY_AUTH_TOKEN: 'environment-ntfy-token',
+    });
+    const withoutToken = store.load({
+      OPENROUTER_API_KEY: 'environment-key',
+      WEB_DASHBOARD_TOKEN: 'environment-dashboard-token',
+    });
+
+    expect(withToken?.pushNotifications.topic).toBe('redditbot-7f3a9c21');
+    expect(withToken?.pushNotifications.authToken).toBe('environment-ntfy-token');
+    expect(withoutToken?.pushNotifications.authToken).toBeUndefined();
+  });
+
   it('updates the singleton record instead of appending versions', () => {
     store.save(getTestConfig());
     store.save(getTestConfig({ browser: { sessionDir: './data/browser-session', dryRun: true } }));