BuildHelpers revival

Tracking issue for bringing BuildHelpers from status-incoming to status-active.
Steward: @tablackburn. Repo: https://github.com/PowerShellOrg/BuildHelpers.

Each phase is a sub-issue below. Phases overlap; pace to the state of the repo, not the
week numbers. Reference material (comment templates, decision tree, YAML, release steps) is in
the Revival Playbook.

Baseline (captured at transfer)

These numbers go in the first release announcement. (Corrected by hand to transfer-time values; the generator ran after the caller workflow commit and six interim issues.)

Working with an AI assistant

Point it at the playbook and this issue. It drafts; you post. Comments on other people's
issues, PR closes, and merges are yours to click.