Stack position: 5 of 7

Two reusable workflow_call workflows. These are the shared CI/CD infrastructure that Plaster and PSDepend will adopt immediately after this PR merges.

What's in this PR

powershell-ci.yml (reusable):

• Matrix: Windows/Ubuntu/macOS × PS 5.1 (Windows only) + PS 7.x = 4 legs total
• NuGet provider bootstrap step for PS 5.1 before module install
• Installs: psake, PowerShellBuild, PSScriptAnalyzer, Pester 5 (pinned to 5.0–5.99)
• Fixed psake task sequence: Init → Test → Analyze
• Uploads test result artifacts per matrix leg (testResults.xml)

powershell-release.yml (reusable):

• Inputs: module-name (required string), create-github-release (bool, default true)
• Required secret: PSGALLERY_API_KEY
• Runs full CI gate (Init → Test → Analyze) before Build → Publish
• Creates GitHub Release with auto-generated notes via gh release create --generate-notes
• Release runs on windows-latest only (publish from Windows for maximum compatibility)

Consuming repo usage:

# ci.yml
jobs:
  ci:
    uses: PowerShellOrg/.github/.github/workflows/powershell-ci.yml@main

# release.yml (tag-triggered)
jobs:
  release:
    uses: PowerShellOrg/.github/.github/workflows/powershell-release.yml@main
    with:
      module-name: PSDepend
    secrets:
      PSGALLERY_API_KEY: ${{ secrets.PSGALLERY_API_KEY }}

Council questions

1. Pester version pin (5.0–5.99): intentional — keeps us on Pester 5.x and excludes a hypothetical Pester 6 that might be breaking. Agree?
2. Release runs Windows-only: Publish-Module is most reliable from Windows. Any objection?
3. --generate-notes for GitHub Releases: this pulls from PR titles since last release. Only useful once PRs are the standard workflow. For the first release, maintainers should write notes manually. Should we document this caveat?
4. Init task in CI: this assumes every repo has an Init psake task. If a repo doesn't define it, CI will fail. Is the org wiki the right place to document required task names, or should we add a REQUIRED_TASKS.md here?

Base: pr/04-templates — merge PRs 1–4 first.