Issue Description

Add a CI job that validates all PowerShell files (.ps1, .psm1, .psd1) contain the required Microsoft copyright and MIT license header at the top of the file.

Required Header Format

# Copyright (c) Microsoft Corporation.
# Licensed under the MIT license.

The header must appear at the very beginning of the file (lines 1-2). Additional metadata comments (purpose, author) may follow but are not required.

Acceptance Criteria

• Create validation script in scripts/linting/ that checks all PowerShell files
• Script returns non-zero exit code when files are missing headers
• Script outputs list of non-compliant files with their paths
• Add npm script alias for local execution (e.g., npm run lint:copyright)
• Integrate into existing CI linting workflow
• Document expected header format in scripts/linting/README.md

Additional Context

Files to Check

• All .ps1 files (scripts)
• All .psm1 files (modules)
• All .psd1 files (module manifests)

Exclusions to Consider

• scripts/tests/ directory (test files may have different conventions)
• Vendor/third-party files if any exist

Example Validation Logic

$expectedLine1 = '# Copyright (c) Microsoft Corporation.'
$expectedLine2 = '# Licensed under the MIT license.'

$content = Get-Content -Path $file -TotalCount 2
if ($content[0] -ne $expectedLine1 -or $content[1] -ne $expectedLine2) {
    # File is non-compliant
}

Related

• Existing linting scripts in scripts/linting/
• PSScriptAnalyzer integration at scripts/linting/Invoke-PSScriptAnalyzer.ps1