Pull Request Overview

This PR adds comprehensive GitHub Copilot instructions for the IONOS Nextcloud Workspace configuration project. The instructions provide detailed guidance on project context, coding standards, development workflow, and code review processes.

• Establishes project-specific AI assistant guidelines covering PHP coding standards, Nextcloud configuration patterns, and IONOS-specific requirements
• Documents code review processes with conventional comment types and review checklists
• Provides comprehensive development workflow guidance including build processes, testing requirements, and troubleshooting

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