✨ Set up GitHub Copilot instructions for SSVC repository

[Copilot]

• Create .github/copilot-instructions.md file with repository-specific guidance
• Include project overview and technology stack information
• Add development workflow instructions
• Specify coding conventions and best practices
• Document testing and validation requirements
• Add deployment and documentation guidelines
• Address review feedback:
  • Added Make as build tool in Technology Stack
  • Standardized command patterns (local/Docker)
  • Added return type hints requirement
  • Expanded /src/ssvc/ structure description
  • Removed redundant sections
  • Updated API documentation URLs
  • Clarified license type
  • Added Make Commands section
  • Removed obsolete --project src references
  • Added /doc/ and /pdfs/ to obsolete directories list
• Restore aspirational guidance:
  • Added back JSON/CSV naming convention as aspirational guidance
  • Restored JSON Regeneration pitfall for developers without commit hooks

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 #1011

---

💡 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.

[Copilot]

Pull Request Overview

This PR adds comprehensive GitHub Copilot instructions to enhance AI-assisted development in the SSVC repository by providing detailed project context, development guidelines, and best practices.

• Creates a structured 203-line instructions file covering project overview, technology stack, and development workflow
• Establishes coding conventions, testing requirements, and documentation guidelines
• Identifies common pitfalls and provides troubleshooting guidance

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[sei-renae]

attempting to get my comments out of Pending Purgatory