feat(web): drop '· last admin' label from user row

The Demote/Delete buttons are already disabled with proper tooltips
implied by their disabled state; the extra inline label was visual
clutter on the only-admin's own row.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/src/app/settings/users/user-row-client.tsx

@@ -76,11 +76,6 @@ export function UserRowClient({ user, isSelf, isLastAdmin }: UserRowClientProps)
             {isSelf && (
               <span className="text-xs text-muted-foreground">you</span>
             )}
-            {isAdmin && isLastAdmin && (
-              <span className="text-xs text-muted-foreground">
-                · last admin
-              </span>
-            )}
           </div>
         </div>
         <div className="flex flex-wrap justify-end gap-1">