feat(KB-045): add scheduled tasks automation system

- Add AutomationStore and core automation types for cron-based scheduling
- Implement CronRunner engine for executing scheduled automations
- Add REST API routes for CRUD operations on automations
- Create UI components: ScheduleCard, ScheduleForm, and ScheduledTasksModal
- Integrate scheduled tasks into dashboard App.tsx and CLI dashboard command
- Add comprehensive tests for store, runner, API, and UI components
- Include changeset for the new scheduled tasks feature

packages/engine/src/index.ts

@@ -12,3 +12,4 @@ export { isUsageLimitError, UsageLimitPauser } from "./usage-limit-detector.js";
 export { PrMonitor, type PrComment, type TrackedPr, type OnNewCommentsCallback } from "./pr-monitor.js";
 export { PrCommentHandler } from "./pr-comment-handler.js";
 export { NtfyNotifier, type NtfyNotifierOptions } from "./notifier.js";
+export { CronRunner, type CronRunnerOptions } from "./cron-runner.js";