Add C# SDK for Gopher MCP with C Binding Support

[bettercallsaulj]

Overview

We need to extend the Gopher MCP SDK by adding C binding support in C#.
This will allow to interact with the native C library directly for C# developers, enabling seamless integration between low-level bindings and high-level MCP abstractions.

Requirements

• Implement C binding layer in the C# SDK.
• Expose a clean C# interface for interacting with the C functions.
• Ensure proper error handling, memory management, and async compatibility.
• Provide unit tests for the binding layer.
• Add documentation and usage examples.
• Support working on Windows and macOS(for developing).

Deliverables

• Updated C# SDK with C binding.
• Example code demonstrating initialization and function calls.
• Documentation for setup and usage.

PR

#105