feat: implement comprehensive solution modernization (CPM, KRaft, formatting)

[ffernandolima]

🎯 Overview

This PR implements Central Package Management (CPM) across the entire Confluent.Kafka.Core solution, centralizing all NuGet package version management into a single Directory.Packages.props file with explicit package source configuration. Additionally, it standardizes code formatting and modernizes the development infrastructure.

📋 What Changed

• ✅ Added Directory.Packages.props with centralized package version definitions
• ✅ Added NuGet.Config for explicit package source management and security
• ✅ Removed Version attributes from all PackageReference elements across 13 projects
• ✅ Organized packages into logical, alphabetically-sorted sections for better maintainability
• ✅ Enabled ManagePackageVersionsCentrally property for solution-wide consistency
• ✅ Standardized indentation to 4 spaces across all project files (converted from tabs)
• ✅ Fixed encoding issues and removed BOM signatures for clean UTF-8
• ✅ Migrated Docker Compose from Zookeeper to modern KRaft mode
• ✅ Resolved integration test failures with Kafka and Schema Registry infrastructure

🏗️ Package Organization

Packages are now organized in alphabetically-sorted sections:

• Caching and Storage Packages - Redis and storage dependencies
• Confluent Packages - Kafka and Schema Registry packages
• Microsoft Extensions Packages - Configuration, hosting, and logging abstractions
• Observability Packages - OpenTelemetry and monitoring tools
• Resilience and Retry Packages - Polly and resilience patterns
• Serialization Packages - JSON, Protobuf, and serialization libraries
• Testing Packages - Test frameworks, utilities, and reporting tools

🔒 Package Source Configuration

• NuGet.Config - Explicit package source mapping for enhanced security
• Source Mapping - Formal package resolution configuration
• Security Enhancement - Improved package supply chain security
• Environment Consistency - Consistent package resolution across development environments

🎨 Code Formatting Standardization

• Indentation: Converted all 13 project files from tabs to 4 spaces
• Encoding: Standardized to UTF-8 without BOM signatures
• Consistency: Uniform formatting across entire solution
• Cross-Platform: Better compatibility with different editors and tools

🐳 Infrastructure Modernization

• KRaft Mode: Migrated Kafka from Zookeeper-based to modern KRaft architecture
• Simplified Setup: Reduced from 5 to 4 Docker services (removed Zookeeper)
• Faster Startup: Eliminated Zookeeper bootstrap delays
• Test Reliability: Fixed integration test failures with Kafka controller timeouts
• Future-Proof: Aligned with Kafka's strategic direction

🚀 Benefits

• 📦 Single Source of Truth - All package versions managed from one location
• 🔄 Easier Updates - Update package versions once, applies everywhere
• 🛡️ Version Consistency - Eliminates version conflicts across projects
• 📚 Better Organization - Logical grouping makes dependencies easy to find
• 🧹 Cleaner Project Files - Reduced noise in individual .csproj files
• 🔒 Enhanced Security - Explicit package source mapping prevents supply chain attacks
• ⚡ Future-Proof - Follows NuGet 6.2+ best practices
• 🎯 Prevents Warnings - Avoids NU1507 warnings in multi-source scenarios
• 🎨 Professional Formatting - Consistent 4-space indentation and UTF-8 encoding
• 🚀 Modern Infrastructure - KRaft mode for improved performance and reliability

🔧 Technical Details

• NuGet Version: Requires NuGet 6.2+ (Visual Studio 2022 17.2+, .NET SDK 6.0.300+)
• Projects Affected: 13 projects across src/ and tests/ directories
• Package Count: 18 unique packages centrally managed
• Configuration Files: Directory.Packages.props + NuGet.Config for complete package management
• Code Formatting: Standardized 4-space indentation, UTF-8 without BOM
• Docker Infrastructure: KRaft mode Kafka setup with cluster ID configuration
• Backward Compatibility: Fully compatible with existing build processes

✅ Testing

• Solution restores successfully
• All projects build without errors
• Package versions resolve correctly
• Package source configuration works as expected
• No NU1507 warnings generated
• Integration tests pass with new Kafka infrastructure
• Schema Registry connectivity working
• No breaking changes to existing functionality

📖 Documentation

Follows Microsoft's Central Package Management guidelines and industry best practices for package source security.

⚠️ Breaking Changes

• KRaft Migration: Zookeeper-based Kafka setup replaced with KRaft mode

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Migration Impact: This comprehensive modernization makes future dependency management significantly easier, more secure, and more reliable across the entire solution while providing a more robust development infrastructure.

[Copilot]

Pull Request Overview

Implements Central Package Management (CPM) by centralizing all NuGet package versions into a single Directory.Packages.props and adding an explicit NuGet.Config, then cleaning up individual project files.

• Added Directory.Packages.props for centralized version definitions and grouping
• Added NuGet.Config for explicit package source mapping
• Removed Version attributes from all <PackageReference> entries in 13 projects and updated the solution file

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/Confluent.Kafka.Core.Tests/Confluent.Kafka.Core.Tests.csproj	Removed Version attributes from test package references
tests/Confluent.Kafka.Core.Shared.Tests/Confluent.Kafka.Core.Shared.Tests.csproj	Removed Version attributes from shared test package references
src/**/*.csproj	Removed Version attributes across all production package references
NuGet.Config	Added explicit package source mapping
Directory.Packages.props	Introduced centralized <PackageVersion> definitions
Confluent.Kafka.Core.sln	Added Directory.Packages.props and NuGet.Config to solution items

Comments suppressed due to low confidence (2)

tests/Confluent.Kafka.Core.Tests/Confluent.Kafka.Core.Tests.csproj:31

• Consider adding PrivateAssets="all" to test-only dependencies (Microsoft.NET.Test.Sdk, Moq, xunit) to prevent them from flowing transitively to consuming projects.

		<PackageReference Include="Microsoft.NET.Test.Sdk" />

tests/Confluent.Kafka.Core.Shared.Tests/Confluent.Kafka.Core.Shared.Tests.csproj:29

• Shared tests also reference configuration and test frameworks; add PrivateAssets="all" on PackageReference elements that should not be transitive.

		<PackageReference Include="Microsoft.Extensions.Configuration" />