[BACKEND] Implement Asset Assignment Module

[yusuftomilola]

Description:
This module manages the assignment of assets to specific employees, departments, or branches. For example, a laptop can be assigned to a staff member while a truck can be assigned to a logistics department.

Expected Behavior:

• Table asset_assignments with fields assetId, assignedToUserId (optional), assignedToDepartmentId, assignmentDate.
• API to assign/unassign assets.
• Historical records of previous assignments.

Tasks:

• Generate asset-assignments module.
• Create entity + DTOs.
• Add service methods for assignment/unassignment.
• Implement controller endpoints.

[Tinna23]

can i work on this?