Add Go SDK Migrator agent

[omgitsads]

Adds a Go SDK migrator custom copilot agent for #1415 that will be used to migrate the Tools

[Copilot]

Pull Request Overview

This PR adds a custom Copilot agent specification document that provides detailed instructions for migrating MCP tools from the mark3labs/mcp-go library to the modelcontextprotocol/go-sdk library. The agent is designed to work independently on assigned toolsets and includes comprehensive migration guidelines.

Key Changes

• Added Go SDK Tool Migrator agent documentation with step-by-step migration instructions
• Included detailed schema migration examples showing the conversion from DSL-based to JSON Schema format
• Provided guidance on worktree setup, test updates, and toolsnaps validation

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.