Delete a schedule

Deletes the schedule. Pass ?cascade=true (or cascade: true in the body) to also cancel all non-terminal assignments spawned by this schedule. Caller must be the creator or admin.

Authorization model — partition-key trust. Same as GET / PATCH: non-admin callers delete with their own UPN as the Cosmos partition key, so attempting to delete someone else’s schedule returns 404 (not 403). Admin callers use a cross-partition lookup to resolve the real owner before deleting.