Summary:

• Split the PyPI release workflow into separate build and publish jobs.
• Keep id-token: write only on the publish job.
• Pass built distributions through GitHub Actions artifacts.

Validation:

• Local checks passed: 118 tests, Ruff, text hygiene, git whitespace.
• Pre-push full passed.
• Changed file only: .github/workflows/publish-pypi.yml.

Risk:

• Low. Release publishing still only runs on release: published.
• Trusted Publishing cannot be fully exercised until the real release event.

Rollback:

• Revert this PR to restore the previous single-job publish workflow.