Display Number of Users in Each Role

[mkimberlin]

As a system administrator,
I want to view the number of users assigned to each role
So that I can quickly understand the distribution of users across different roles.

Acceptance Criteria:

• When I navigate to the role administration page, I should see a summary displaying the number of users in each role.
• The summary section should update dynamically when users are added or removed from roles.
• The number of users should be displayed next to each role name.