- Add auto-start functionality to cron service when jobs are added
if service is not running and event loop is available
- Add 'reminder' field to CronPayload to distinguish between
simple reminders (send message directly) and tasks (execute via agent)
- Update cron tool to accept 'reminder' parameter
- Fix callback logic to check reminder field: reminders send directly,
tasks are processed through agent
- Ensures both 'remind me to X' and 'schedule a task to do X' work correctly