Remove capacity and status validation from organizer assign flow so
organizers can intentionally overbook shifts. Log overbooked assignments
for audit trail. Volunteer claims still enforce hard limits. Frontend
shows a warning banner when a shift is full and requires confirmation
before overbooking.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Implements the complete ShiftAssignment lifecycle:
- ShiftAssignmentStatus enum with allowed transitions
- ShiftAssignmentService with claim/assign/approve/reject/cancel/bulkApprove
- ShiftAssignmentController with event-scoped endpoints
- ShiftAssignmentPolicy (organizer + volunteer self-cancel)
- VolunteerAvailability model, controller, and sync endpoint
- Refactored ShiftController to delegate to service layer
- 31 workflow tests covering all paths and multi-tenancy
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
