- add standard script header to pester.config.ps1
- add standard module header to GitMocks.psm1
- add .DESCRIPTION to Initialize-GitMocks and Initialize-MockGitHubEnvironment
- fix Test-Path mock filter to catch implicit Leaf checks

🔧 - Generated by Copilot

…ntegration (#204)

# Pull Request

## Description

Adds a reusable GitHub Actions workflow for running Pester tests across
the repository and integrates it into the PR validation pipeline. This
provides standardized PowerShell testing infrastructure that blocks PRs
with failing tests.

Key features:

- **Reusable pester-tests.yml workflow**:
- `workflow_call` trigger enables reuse from other workflows via `uses:
./.github/workflows/pester-tests.yml`
- Configurable inputs: `soft-fail` (default: false),
`changed-files-only` (default: true)
  - Pester 5.x with `-CI` configuration for CI-optimized output
  - Artifact upload persists NUnit XML results for 30 days

- **PR validation integration**:
  - Adds `pester-tests` job to pr-validation.yml
  - Configured with `soft-fail: false` to block PRs with failing tests
  - Uses `changed-files-only: true` for efficiency

- **Security**:
  - All GitHub Actions are SHA-pinned to prevent supply chain attacks
  - Uses `persist-credentials: false` on checkout
  - Minimal `contents: read` permission scope

## Related Issue(s)

Closes #194
Closes #195

## Type of Change

Select all that apply:

**Code & Documentation:**

- [ ] Bug fix (non-breaking change fixing an issue)
- [ ] New feature (non-breaking change adding functionality)
- [ ] Breaking change (fix or feature causing existing functionality to
change)
- [ ] Documentation update

**Infrastructure & Configuration:**

- [x] GitHub Actions workflow
- [ ] Linting configuration (markdown, PowerShell, etc.)
- [ ] Security configuration
- [ ] DevContainer configuration
- [ ] Dependency update

**AI Artifacts:**

- [ ] Reviewed contribution with `prompt-builder` chatmode and addressed
all feedback
- [ ] Copilot instructions (`.github/instructions/*.instructions.md`)
- [ ] Copilot prompt (`.github/prompts/*.prompt.md`)
- [ ] Copilot chatmode (`.github/chatmodes/*.chatmode.md`)

**Other:**

- [ ] Script/automation (`.ps1`, `.sh`, `.py`)
- [ ] Other (please describe):

## Testing

- Validated YAML syntax
- Confirmed workflow structure matches existing patterns
(ps-script-analyzer.yml)
- Verified SHA pins match approved versions in tool-checksums.json

## Checklist

### Required Checks

- [x] Documentation is updated (if applicable)
- [x] Files follow existing naming conventions
- [x] Changes are backwards compatible (if applicable)

### AI Artifact Contributions

N/A - This PR does not include AI artifacts.

### Required Automated Checks

The following validation commands must pass before merging:

- [x] Markdown linting: `npm run lint:md`
- [x] Spell checking: `npm run spell-check`
- [x] Frontmatter validation: `npm run lint:frontmatter`
- [x] Link validation: `npm run lint:md-links`
- [x] PowerShell analysis: `npm run lint:ps`

## Security Considerations

- [x] This PR does not contain any sensitive or NDA information
- [x] Any new dependencies have been reviewed for security issues
- [x] Security-related scripts follow the principle of least privilege

**Security notes:**

- Uses `persist-credentials: false` on checkout to prevent credential
leakage
- Minimal `contents: read` permission scope at both workflow and job
levels
- All GitHub Actions are SHA-pinned to prevent supply chain attacks:
  - `actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8` (v4.2.2)
- `actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f`
(v4.4.3)

## Additional Notes

This workflow builds on the Pester infrastructure established in #202
(pester.config.ps1, GitMocks.psm1). Future PRs will add actual test
files that leverage this workflow.