Add admin queue assignment

[azahjessica49-commits]

Close: #260

I've successfully implemented admin queue assignment functionality. Here's what was completed:

Data Model Changes
Added assignedTo and assignedAt fields to VerificationRequest type in verification.service.ts
Added assignedTo and assignedAt fields to ReviewReport type in review.ts
Service Layer
Added assignRequest() and unassignRequest() methods to verification.service.ts
Added assignReport() and unassignReport() methods to review-report.service.ts
Added getter methods for assigned/unassigned requests and reports
Audit Logging
Added new audit actions: verification_assigned, verification_unassigned, report_assigned, report_unassigned to audit-log.ts
Updated audit log service to validate the new actions
All assignment changes are now logged with actor, target, and metadata
UI Implementation
Added filter buttons (All, Assigned to me, Unassigned) for both verification requests and review reports
Added assignment controls with smart button states:
"Assign to me" for unassigned items
"Reassign to me" for items assigned to others
"Unassign" for items assigned to current admin
Visual badges showing assignment status with truncated admin addresses
Filters properly filter the displayed items based on assignment state
Acceptance Criteria Met
✅ Admins can assign requests to themselves or another admin
✅ Queue filters include assigned to me and unassigned
✅ Assignment changes are audit logged

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[azahjessica49-commits]

Done, close: #322

[azahjessica49-commits]

kindly merge PR