Issue Description

The repository needs GitHub Copilot instruction files to provide context-specific guidance for code generation and editing tasks.

Additional Context

Files to add:

• .github/copilot/instructions/markdown.instructions.md - Markdown file editing guidance
• .github/copilot/instructions/powershell.instructions.md - PowerShell script guidance
• .github/copilot/instructions/yaml.instructions.md - YAML/workflow file guidance

Priority: Wave 1 (Priority 1) - Can merge in parallel with other Wave 1 PRs

Dependencies: None - independent issue

Testing: Validate markdown syntax, verify instruction files are recognized by Copilot, test context-specific suggestions