Admin-only page at /admin with:
- Create user form (username, password, admin toggle)
- User list table with edit and delete actions
- Inline user editing (change password, toggle admin role)
- Inline permission editor with per-app checkboxes grouped by server
- Access guarded by checking is_admin from /api/auth/me
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>