Issue Description

The repository needs reusable workflow files for validation tasks including linting, spell-checking, markdown validation, link checking, and frontmatter validation.

Additional Context

Files to add:

• .github/workflows/reusable-powershell-lint.yml - PowerShell linting workflow
• .github/workflows/reusable-spellcheck.yml - Spell checking workflow
• .github/workflows/reusable-markdown-lint.yml - Markdown linting workflow
• .github/workflows/reusable-markdown-link-check.yml - Link validation workflow
• .github/workflows/reusable-link-lang-check.yml - Combined link and language check
• .github/workflows/reusable-frontmatter-validation.yml - Frontmatter validation workflow
• .github/workflows/reusable-npm-audit.yml - NPM security audit workflow

Priority: Wave 3 (Priority 3) - Depends on Wave 2 completion

Dependencies: Requires linting scripts from Issues #9 and #10, and configurations from Issue #3

Testing: Validate YAML syntax, test each reusable workflow with sample inputs, verify workflow can be called from other workflows