Create Bulk Sync Schedule

Adds a new schedule to a bulk sync.

A bulk sync can have multiple schedules attached; adding one here does not replace existing schedules. Schedule times are interpreted in UTC.

Creating a schedule only affects future automatic executions. To run the sync immediately, call POST /api/bulk/syncs/{id}/executions.

To sync the two selective groups of objects at different frequencies, add one schedule with selectiveMode set to incrementalFields and another with nonincrementalFields. Set the default schedule to manual to avoid an additional automatic run covering all selected objects. Check capabilities.supports_selective_modes on GET /api/connections/{id}/bulksync/source first.