feat(ci): Integrate release notes job into release pipeline and add backfill workflow

[sfreudenthaler]

Summary

Two workflow changes: (1) Add a release-notes job to the existing cicd_6-release.yml pipeline, and (2) create a standalone backfill workflow for populating notes on past releases.

Acceptance Criteria

Release pipeline integration (cicd_6-release.yml)

• New release-notes job added after the release job
• needs: [release-prepare, release] — waits for GitHub release to exist
• if: success() — only runs if release succeeded
• Does NOT block finalize (uses if: always()) or report
• Passes release_tag and release_version from release-prepare outputs
• Passes ANTHROPIC_API_KEY and CI_MACHINE_TOKEN secrets

Backfill workflow (cicd_ai-release-notes-backfill.yml)

• workflow_dispatch trigger with release_tag input
• Calls the same reusable component (cicd_comp_ai-release-notes-phase.yml)
• Concurrency control per tag (release-notes-${{ inputs.release_tag }})
• run-name shows the tag being processed

Job placement

release-prepare → build → deployment → release → release-notes
                                                ↘              ↘
                                          finalize (always)   report (always)

Technical Details

Files:

• .github/workflows/cicd_6-release.yml — added release-notes job (lines 163-175)
• .github/workflows/cicd_ai-release-notes-backfill.yml — new standalone workflow

Use cases for backfill workflow:

• Populate notes on past releases that were created with empty descriptions
• Re-generate notes after clearing the body (idempotency: skips if body has content)
• Test the pipeline in isolation

Status: ✅ Implemented

References

• Parent Epic: epic(ci): Automated release notes for GitHub releases #35011
• Test PR: dotCMS/core-workflow-test#451