feat: implement admin dashboard API endpoints

[Xhristin3]

Add role-based admin system with endpoints for platform oversight
including user management, escrow listing, and system statistics.

• Add UserRole enum with USER, ADMIN, SUPER_ADMIN
• Create AdminGuard for role-based access control
• Implement AdminModule with AdminController and AdminService
• Add GET /admin/escrows with advanced filtering
• Add GET /admin/users with pagination
• Add GET /admin/stats for platform statistics
• Add POST /admin/users/:id/suspend for user management
• Include admin seed script for development
• Add comprehensive e2e tests for admin endpoints"

closes #65

[Cedarich]

Fix lint errors

[Xhristin3]

@Cedarich done
please make the workflow automatic

[Cedarich]

Please npm run lint and address lint errors.

thank you for the solid implementation

[Xhristin3]

@Cedarich done.