Add creator role buttons to admin user management

src/app/admin/AdminUsers.tsx

@@ -90,30 +90,25 @@ export default function AdminUsers({
                         Unsuspend
                       </button>
                     ) : null}
-                    {u.role === "learner" ? (
+                    {u.role !== "admin" && (
                       <button className="btn ghost" style={btn} disabled={busy} onClick={() => act(u.id, "role", "admin")}>
                         Make admin
                       </button>
-                    ) : (
+                    )}
+                    {u.role !== "creator" && (
                       <button
                         className="btn ghost"
                         style={btn}
                         disabled={busy || isLastAdmin}
                         title={isLastAdmin ? "Can't demote the only admin" : undefined}
-                        onClick={() => act(u.id, "role", "learner")}
+                        onClick={() => act(u.id, "role", "creator")}
                       >
-                        Make learner
+                        Make creator
                       </button>
                     )}
-                  </div>
-                </td>
-              </tr>
-            );
-          })}
-        </tbody>
-      </table>
-    </div>
-  );
-}
-
-const btn: React.CSSProperties = { minHeight: 36, padding: "6px 12px", fontSize: "0.85rem", boxShadow: "none" };
+                    {u.role !== "learner" && (
+                      <button
+                        className="btn ghost"
+                        style={btn}
+                        disabled={busy || isLastAdmin}
+