Migrate chapter 4 main solution to .NET 10 and add central package management

[meaboutsoftware]

📋 Description

This PR migrates Chapter 4 main solution (Fitnet) to .NET 10, introduces Central Package Management for better dependency consistency, and fixes GitHub Actions workflow authentication issues with the GitHub Packages NuGet feed.

Key Changes:

• Migrated all projects from .NET 9 to .NET 10
• Implemented Central Package Management using Directory.Packages.props
• Fixed workflow authentication by switching from add source to update source with local config file
• Updated all NuGet packages to their latest .NET 10 compatible versions

Issue Resolved: Build pipeline was failing with "The name specified has already been added to the list of available package sources" due to attempting to add a source that already existed in local nuget.config.

📦 PR Includes

• Feature added 🆕 (Central Package Management)
• Bug fix 🐛 (GitHub Actions workflow authentication)
• Code refactor 🔄 (.NET 10 migration, package consolidation)
• Documentation update 📚
• Tests added/updated 🧪
• Other: Infrastructure upgrade to .NET 10

🚫 PR Does Not Include

• Breaking changes ❌
• Major architectural changes 🏗️
• Unrelated features/tasks 🚫

💡 Additional Notes

Central Package Management Benefits:

• Single source of truth for all package versions in Directory.Packages.props
• Eliminates version conflicts across projects
• Simplifies dependency updates and maintenance
• Aligns with .NET best practices and modern solution structure

Workflow Fix Details:

• Changed authentication approach from adding new source to updating existing source
• Added --configfile nuget.config to work with local configuration instead of global
• Fixed variable references: now using ${{ github.repository_owner }} and ${{ secrets.GITHUB_TOKEN }}
• Corrected source name casing to EvolutionaryArchitecture (matching nuget.config)

Testing:

• ✅ Solution builds successfully locally and in CI/CD
• ✅ All existing tests pass
• ✅ Package restore works with authenticated GitHub Packages feed
• ✅ GitHub Actions workflow completes without errors