✨ Set up Copilot instructions for Canada.ca design system repository

[Copilot]

This PR implements GitHub Copilot instructions to improve AI-assisted development experience for the Canada.ca design system repository, as requested in issue #[issue_number].

What's Added

Added .github/copilot-instructions.md with comprehensive guidance for AI assistants working on this repository, including:

• Project context: Canada.ca Design System Library with bilingual documentation requirements
• Language guidelines: French-first bilingual content policy following Canadian government standards
• Technical specifications: Jekyll static site generator conventions, HTML validation requirements, and accessibility standards
• File structure: Documentation of existing directory organization and naming patterns
• Design system principles: Guidance for maintaining consistent design patterns and templates
• Contribution workflow: Integration with existing community processes

Why This Matters

The instructions provide essential context about:

• Bilingual requirements (French/English) critical for Canadian government content
• Jekyll-based architecture and YAML front matter conventions
• Government accessibility and content standards (WCAG compliance)
• Design system pattern consistency across templates and components
• HTML validation processes using vnu-jar

Implementation Details

The instructions follow GitHub's standard format and are automatically discovered by Copilot. They emphasize the repository's unique characteristics as official Canadian government design system documentation, ensuring AI suggestions align with:

• Canadian government language policy (French-first)
• Accessibility requirements and semantic HTML practices
• Existing file structure and naming conventions
• Design system governance and contribution processes

This implementation provides the foundation for more effective AI-assisted development while maintaining the high standards expected for official government design documentation.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #422

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[netlify]

✅ Deploy Preview for systeme-conception-canada-ca ready!

Name	Link
🔨 Latest commit	cdb7a0a
🔍 Latest deploy log	https://app.netlify.com/projects/systeme-conception-canada-ca/deploys/68d55a531b8dfa000882c753
😎 Deploy Preview	https://deploy-preview-423--systeme-conception-canada-ca.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.
Lighthouse	1 paths audited Performance: 72 Accessibility: 88 Best Practices: 83 SEO: 99 PWA: - View the detailed breakdown and full score reports

---

To edit notification comments on pull requests, go to your Netlify project configuration.