feat(automation): add daily briefing preset and cron backup scheduling

src/automation/index.ts

@@ -3,3 +3,4 @@ export { WebhookHandler } from './webhooks.js';
 export { GmailWatcher } from './gmail.js';
 export { HeartbeatMonitor, parseInterval } from './heartbeat.js';
 export type { HeartbeatResult, HeartbeatDeps, CheckResult } from './heartbeat.js';
+export { buildPresetCronJobs } from './presets.js';