Enhances data integrity with automated cleanup

[dpanta94]

Improves Shepherd's data integrity and efficiency by implementing automated database cleanup:

• Introduces a "Herding" task to periodically remove orphaned task data.
• Adds automatic cleanup of task data when Action Scheduler deletes actions, preventing orphaned records.
• Documents database cleanup strategies and API changes.

[lucatume]

The code looks fine, but I think testing should be improved and simplified.