[FE-20] Complete Users page with role management UI in opsce folder

[yusuftomilola]

Problem

frontend/app/(dashboard)/users/page.tsx exists but is empty. Admins cannot view, manage, or update user roles through the UI.

Proposed Solution

Create frontend/opsce/features/users/UsersPage.tsx. Fetch users from GET /api/users (ADMIN only). Allow role changes inline and support soft-delete.

Acceptance Criteria

• Users listed in a table with columns: Full Name, Email, Role, Verified, Created At, Actions
• Role shown as a color-coded badge (ADMIN = red, MANAGER = blue, VIEWER = gray)
• An inline role dropdown allows ADMIN users to change another users role
• "Deactivate" button soft-deletes a user with a confirmation dialog
• An "Invite User" button opens a modal with email and role fields
• Page restricted to ADMIN role — non-admins see a 403 Forbidden message
• Pagination and search by email/name

[Windowlight]

@Windowlight has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I’m interested in this issue and believe my experience with contracts, backend systems, and frontend implementation makes me a good fit. Happy to provide updates as I work through it.

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[kilodesodiq-arch]

@kilodesodiq-arch has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi, I am a fullstack developer with years of expereience, please assign me this issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @kilodesodiq-arch to this issue.

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This issue has been completed by @kilodesodiq-arch as part of the Stellar Wave Program's 5th Wave 🥳

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