Implement cron job management system for scheduled tasks (similar to OpenAI's Pulse but the AI can also schedule jobs)

- Introduced a new cron job system allowing users to schedule automated tasks via the CLI, supporting one-time reminders and recurring jobs.
- Added commands for managing cron jobs: `/cron` to list jobs, `/cron add` to create new jobs, and `/cron remove` to delete jobs.
- Implemented job storage in `~/.hermes/cron/jobs.json` with output saved to `~/.hermes/cron/output/{job_id}/{timestamp}.md`.
- Enhanced the CLI and README documentation to include detailed usage instructions and examples for cron job management.
- Integrated cron job tools into the hermes-cli toolset, ensuring they are only available in interactive CLI mode.
- Added support for cron expression parsing with the `croniter` package, enabling flexible scheduling options.

requirements.txt

@@ -30,5 +30,5 @@ platformdirs
 # modal
 # boto3
 
-# Optional: Legacy Hecate terminal backend
-# git+ssh://git@github.com/NousResearch/hecate.git
+# Optional: For cron expression parsing (cronjob scheduling)
+croniter