Add comprehensive README.md file for Conductor framework

[Copilot]

This PR adds a comprehensive README.md file to document the Conductor framework, addressing the need for proper project documentation.

What's Added

The README provides complete documentation for the Conductor framework, including:

📋 Core Documentation

• Framework Overview: Clear description of the mediator pattern implementation with advanced features
• Key Features: 10 major features including caching, validation, transactions, auditing, authorization, pipelines, saga orchestration, and multi-transport support
• Architecture Diagram: Visual representation of the layered architecture showing how components interact

🚀 Developer Experience

• Quick Start Guide: Step-by-step setup with practical code examples
• Installation Instructions: Both project reference and NuGet package options
• Table of Contents: Easy navigation through all sections

📖 Detailed Examples

Comprehensive usage examples for all major features:

• Caching: Configurable expiration and sliding windows
• Validation: FluentValidation and DataAnnotations support
• Transactions: Declarative transaction management with isolation levels
• Auditing: Comprehensive logging with customizable categories
• Authorization: Role-based access control
• Pipeline Behaviors: Custom cross-cutting concerns
• Saga Orchestration: Long-running workflows with compensation patterns
• Events: Publishing and handling with automatic routing

⚙️ Configuration & Advanced Usage

• Complete configuration options and middleware setup
• Testing guidance with unit test examples
• Advanced features including custom request types and attributes
• Performance considerations and optimization tips

🤝 Community Support

• Contributing guidelines for open source collaboration
• Support resources with GitHub links
• Professional structure following open source best practices

Technical Details

• Format: GitHub-flavored Markdown with proper syntax highlighting
• Structure: Professional layout with visual badges and emojis for better readability
• Code Examples: Real, working examples based on actual framework implementation
• Version Compatibility: Notes about .NET 9.0+ requirement with guidance for older versions

The README serves as both an introduction for new users and a comprehensive reference for experienced developers, making the Conductor framework more accessible and easier to adopt.

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