Adopt centralized workflows and agentic automation: powershell-beginners #1

Goal

Adopt appropriate centrally maintained actions and reusable workflows from DevOpsDerek/workflows in powershell-beginners. Select agentic automation only after validating the repository's purpose, code, existing CI, and safety boundaries.

Repository-specific focus

Preserve Pester tests and PSScriptAnalyzer checks; consider bounded CI failure diagnosis and course-doc consistency.

Acceptance criteria

• Inventory the repository's current workflow files, tests, toolchain, and access constraints; record verified findings rather than assumptions.
• Use central reusable action/workflow implementations wherever applicable. Keep any local files limited to required caller/trigger or gh-aw source and compiled lock configuration; do not add local-only shared action implementations.
• Pin central references to immutable versions and use least-privilege permissions; use gh-aw safe outputs for agent-proposed changes.
• Keep changes reviewable and require human review. No autonomous merge, release, deploy, infrastructure apply, or publishing.
• Add only repository-relevant automation, document why it fits, and validate it without touching unrelated data or services.
• Keep this issue unassigned in Project Adopt pinned central validation while preserving PowerShell CI #2 Todo until the backlog is complete and the user chooses assignment.