Open a PR to fix the failing GitHub Actions workflow sync-output-repos.yml in ember-cli/ember-cli when runs are triggered on tags.

Context:

• Workflow URL: https://github.com/ember-cli/ember-cli/actions/workflows/sync-output-repos.yml
• The sync-output-repos job succeeds on branches but fails on tag refs.

Task:

1. Inspect the workflow and any scripts/actions it calls.
2. Identify why tag refs cause failure (common causes: assumptions about github.ref_name being a branch, use of refs/heads/* parsing, checkout behavior for tags, version calculation expecting a branch name, or using GITHUB_REF/GITHUB_HEAD_REF incorrectly).
3. Update the workflow (and any referenced scripts) so it works correctly for tag-triggered runs.
   • Ensure the logic correctly distinguishes between refs/tags/* and refs/heads/*.
   • If the workflow needs the associated commit SHA or default branch, use robust GitHub context variables.
   • Keep behavior unchanged for branch pushes.
4. Add/adjust any tests or validation steps feasible for workflows (e.g., echo computed values, guard clauses) to prevent regressions.
5. Ensure the workflow is still secure (no unsafe pull_request_target patterns; avoid untrusted input injection).

Acceptance criteria:

• Workflow completes successfully on both branch pushes and tag pushes.
• Any tag-specific logic is explicit and documented in comments.
• PR includes a clear description of the fix and why it was needed.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: This sync-output-repos job is failing on tags. Can you open a PR to fix it?

Assistant: I’ve kicked off the PR creation process, and we’re currently waiting on your confirmation in the approval dialog before I can proceed with investigating the failing tag runs and opening the fix PR.