chore: Add missing license headers

Author: javierbrea

components/confluence-sync/src/confluence/errors/CustomError.ts

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2025 Telefónica Innovación Digital
+// SPDX-License-Identifier: Apache-2.0
+
 export class CustomError extends Error {
   constructor(...args: ConstructorParameters<typeof Error>) {
     super(...args);

components/confluence-sync/src/confluence/errors/ErrorHelpers.ts

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2025 Telefónica Innovación Digital
+// SPDX-License-Identifier: Apache-2.0
+
 /**
  * Returns the error message from the cause if it is an instance of Error, otherwise returns the cause itself.
  * @param cause Cause of an error. It might be another error, or a string usually