chore: remove dead rettime mock, fix license header typo

- Delete test/__mocks__/rettime.cjs — never loaded (wrong directory for
  auto-mocking, no moduleNameMapper, msw CJS doesn't require rettime directly)
- Fix Apache 2.0 header in utils.test.mjs: 'LICENSE' → 'License'

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sirugh

test/__mocks__/rettime.cjs

@@ -5,7 +5,7 @@ you may not use this file except in compliance with the License. You may obtain
 of the License at http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software distributed under
-the LICENSE is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
+the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
 OF ANY KIND, either express or implied. See the License for the specific language
 governing permissions and limitations under the License.
 */