[WIP] Ensure upgrade tool exists in mcp-server

[Copilot]

Plan: Add upgrade tool to MCP server and update instructions

Understanding the issue:

• The upgrade-agentic-workflows.md instruction file doesn't explicitly mention using the "upgrade" MCP tool
• The "upgrade" tool does NOT exist in the MCP server (only status, compile, logs, audit, mcp-inspect, add, update, fix)
• However, there IS a CLI command gh aw upgrade that exists
• Need to add the upgrade tool to MCP server and update instructions to use it

Checklist:

• Explore repository structure and understand the issue
• Identify that upgrade command exists in CLI but not in MCP server
• Add upgrade tool to MCP server in pkg/cli/mcp_server.go
• Update server help text to list upgrade tool
• Update upgrade-agentic-workflows.md to explicitly mention using upgrade tool
• Update pkg/cli/templates/upgrade-agentic-workflows.md (template version)
• Write tests for the new upgrade tool
• Run make test-unit to validate changes
• Run make agent-finish before committing

Original prompt

Make sure the "upgrade-agentic-workflows.md" instruction involve calling the "upgrade" mcp-server tool. Make sure the upgrade tool exists in mcp-server

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