Add new AssignmentTransfers collection with fields for managing assignment transfer requests:
- requestor, requestedAssignment, currentAssignment (relationships to users/assignments)
- status (pending/approved/rejected/appealed/escalated/completed/cancelled)
- rejectionReason, appealReason (for rejections and appeals)
- transferAt, approvedAt, appealedAt, completedAt (audit timestamps)
- transferLead (relationship to users, current and requested assignment leaders)
- requestMessage, appealMessage (optional context messages)
Add database migrations:
- 20260831_180233_assignment_transfers: Create the main collection table
- 20260901_014006_add_assignment_transfer_event_target: Add assignment-transfers to GameEventLogs target collections
The collection enables the assignment transfer workflow where users can request transfers,
leaders can approve/reject with reasons, and users can appeal rejections.
