Enhance Copilot instructions with comprehensive best practices and guidelines

[Copilot]

Overview

Enhanced the .github/copilot-instructions.md file with comprehensive best practices for GitHub Copilot coding agent, following GitHub's recommended guidelines for repository-specific instructions.

What Changed

Project Structure Updates

• Fixed test project names: Corrected CrystaLearn.Tests to the actual project names CrystaLearn.Test and CrystaLearn.Core.Test
• Added missing projects: Included CrystaLearn.Console and CrystaLearn.Core in the project structure documentation
• Added detailed descriptions: Each test project now has a clear explanation of its purpose

Enhanced Existing Sections

• Command Reference: Updated test commands to reference correct directories and added package restoration command
• Coding Conventions:
  • Added explicit security warnings about never committing secrets
  • Enhanced C# conventions to include modern features (file-scoped namespaces, records)
  • Added specific .editorconfig details (4 spaces indentation, PascalCase for constants)
  • Added requirements for testing (Fix organization name in organization page. ab#16683  #19) and code documentation (Fix organization name in organization page. ab#16683  #20)

New Comprehensive Sections

9. Testing Guidelines

Provides clear guidance on the testing framework and practices:

• Test project structure explanation
• Writing tests best practices using xUnit and AAA pattern
• Running tests commands and configuration

10. Documentation Standards

Establishes documentation expectations:

• XML documentation comments for public APIs
• Inline comments for complex algorithms
• Markdown documentation structure and organization
• Links to existing documentation in /docs directory

11. Contribution Workflow

Integrates with existing contribution documentation:

• References to Contribution Guidelines, Working on Issues, and Setup Development Environment
• Branch strategy (base: develop, features: feature/<name>, fixes: fix/<name>)
• Commit message format guidelines

12. Security and Secrets Management

Emphasizes security best practices:

• Strong warnings about never committing secrets to source control
• dotnet user-secrets usage for local development
• Complete list of required secrets for development
• Projects requiring secret initialization

Impact

These enhancements provide:

1. Better AI-Assisted Development: Copilot has more comprehensive context to generate appropriate code following project conventions
2. Clearer Contributor Guidelines: Human developers have explicit guidance for contributing, testing, and documenting code
3. Improved Security: Explicit warnings about secrets management aligned with best practices
4. Better Integration: References to existing documentation ensure consistency across the project

Statistics

• 79 lines added, 6 lines corrected
• 4 new major sections (Testing, Documentation, Contribution, Security)
• Total: 247 lines of comprehensive guidance

Fixes #<issue_number>

Original prompt

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This section details on the original issue you should resolve

<issue_title>Set up Copilot instructions</issue_title>
<issue_description>Set up Copilot instructions for the repository to guide AI-assisted code suggestions. This should include creating or updating a .github/COPILOT_INSTRUCTIONS.md file with guidelines for code style, best practices, and expectations for Copilot completions.

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 #81

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