Harden release workflow for validated data snapshots

[dlebauer]

Follow-up from review of #12.

Goal

Make release-time data snapshots more repeatable by tying rebuild, validation, and provenance updates together.

Track

• a release-time validation checklist or automation for data snapshots
• ensuring rebuild, validation, and provenance updates run together
• snapshot-oriented release hygiene kept separate from the basic citation and Zenodo work in Release + citation: GitHub release + Zenodo DOI + CITATION.cff #11

Acceptance criteria

• The release workflow defines the required snapshot validation steps.
• Provenance metadata updates are part of that workflow.
• The process is documented clearly enough to run consistently across releases.

[dlebauer]

closing as low priority