feat: add GitHub Pages with MkDocs documentation

[jeremyeder]

Summary

• Add MkDocs configuration with Material theme
• Add GitHub Actions workflow for deploying to GitHub Pages
• Scaffold documentation structure with section outlines

What's Included

MkDocs Configuration (mkdocs.yml)

• Material theme with dark/light mode toggle
• Mermaid diagram support via mermaid2 plugin
• Full navigation structure

Deploy Workflow (.github/workflows/deploy-docs.yml)

• Triggers on push to main when docs/** or mkdocs.yml change
• Builds with mkdocs-material
• Deploys to GitHub Pages

Documentation Structure

docs/
├── index.md                  # Home with exec summary
├── getting-started/
│   ├── installation.md
│   └── first-cba.md
├── patterns/
│   ├── index.md
│   ├── codebase-agent.md
│   ├── issue-to-pr.md
│   └── ... (10 pattern files)
└── resources/
    ├── coloring-book.md
    ├── presentation.md
    └── demo-app.md

Each file contains section outlines with !!! note "Section Summary" blocks indicating content to be written.

After Merge

Once merged, the docs will be available at:
https://jeremyeder.github.io/reference/

The deploy workflow will run automatically on push to main.