Add missing license header to email.test.ts

Author: dahlia

packages/models/src/email.test.ts

@@ -1,3 +1,18 @@
+// DrFed: A web-based platform for developing and debugging ActivityPub apps
+// Copyright (C) 2026 DrFed team
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
 import assert from "node:assert/strict";
 import { describe, it } from "node:test";