Publish CDT++ v1.0.0 and verify the citable release

[acgetchell]

Summary

Publish CDT++ v1.0.0 and verify the citable GitHub and Zenodo release.

This is the last issue in the v1.0.0 release dependency graph. It starts only
after the release-readiness approval in #90 is closed. No implementation, test
design, documentation authoring, dependency modernization, new feature work,
or repository archival belongs here. Post-release stabilization and eventual
archival are tracked separately in #155.

Preconditions

• Approve CDT++ v1.0.0 release readiness #90 is closed with the release commit and validation evidence identified.
• No unresolved issue or pull request blocks publication of v1.0.0.
• The release commit, version/date metadata, release notes, successor links,
  and Zenodo deposition metadata are final.
• The documented clean-checkout validation matrix is green.

Release execution sequence

1. Reconfirm the release commit and required GitHub Actions results.
2. Create and push the annotated v1.0.0 tag.
3. Publish the GitHub release with final notes, limitations, validation
   evidence, and the causal-triangulations successor link.
4. Verify GitHub source archives and every additional release artifact.
5. Publish or finalize the Zenodo record and verify its DOI, metadata, files,
   and links.
6. Record the version-specific Zenodo DOI in CITATION.cff, rerun the metadata
   and documentation checks, and merge that focused post-release commit.
7. Update the repository description and homepage, and confirm that README,
   release, documentation, citation, and successor links remain usable.
8. Confirm that Archive CDT-plusplus after v1.0.0 stabilization #155 is open as the maintenance-only stabilization and
   eventual archival gate, then close Publish CDT++ v1.0.0 and verify the citable release #97.

Acceptance criteria before closing #97

• The v1.0.0 tag and GitHub release are visible and internally consistent.
• The release commit is reproducibly buildable under the published matrix.
• Release artifacts and the stable Zenodo DOI record are verified.
• CITATION.cff contains the concept DOI and the version-specific record DOI
  in their documented roles.
• Repository metadata points to causal-triangulations.
• No unresolved release blocker remains.
• Archive CDT-plusplus after v1.0.0 stabilization #155 is natively blocked by this issue and retains the later archival work.

Post-release handoff

Closing #97 does not archive the repository. Issue #155 remains open for a
maintenance-only stabilization window of owner-determined length. A critical
defect must use a new patch release rather than moving or replacing the
v1.0.0 tag.

[acgetchell]

Completed. I learned a lot.