[FE-35] Build Admin Member Management Table with role editing and ban controls

[devwums]

Problem

The admin panel has no dedicated member management table with controls for role changes, banning, or unbanning. Admins cannot manage users from the UI.

Proposed Solution

Create frontend/cntr/AdminMemberTable/AdminMemberTable.tsx. Props: members: MemberRow[], onRoleChange: (id: string, role: 'USER' | 'ADMIN') => void, onBan: (id: string) => void, onUnban: (id: string) => void. Columns: Avatar + Name, Email, Role (inline dropdown), Status badge, Joined Date, Actions. Ban action requires an inline confirmation step. All implementation must live inside frontend/cntr/.

Acceptance Criteria

• File at frontend/cntr/AdminMemberTable/AdminMemberTable.tsx
• Role dropdown shows USER and ADMIN — calls onRoleChange on change
• Banned members have a red "BANNED" status badge
• Clicking "Ban" shows a confirmation row — requires a second click to confirm
• "Unban" button shown for banned members
• Test in frontend/cntr/AdminMemberTable/AdminMemberTable.test.tsx