bug: GitHub MCP server add_comment tool not accessible from Claude Code

## Summary
Claude Code is unable to invoke the GitHub MCP server's add_comment tool for adding comments to issues. This forces fallback to the gh CLI which has its own issues with backtick handling.

## Observed Behavior
1. Attempted to use mcp__github__add_comment - tool not found
2. Attempted to use mcp__github__create_issue_comment - tool not found
3. The GitHub MCP server has an addIssueComment function in /operations/issues.ts but it doesn't appear to be exposed as an MCP tool
4. Fell back to gh issue comment CLI command which failed due to backtick escaping issues (a known problem that MCP is supposed to solve)

## Expected Behavior
- GitHub MCP server should expose an add_comment or create_issue_comment tool
- This would eliminate the need for CLI workarounds and their associated escaping problems

## Steps to Reproduce
1. Try to add a comment to issue #681
2. Attempt various tool names like mcp__github__add_comment
3. Observe that no comment-related tools are available despite the functionality existing in the codebase

## Impact
This limitation forces use of the gh CLI which:
- Has backtick escaping issues
- Requires more complex command construction
- Defeats the purpose of having MCP servers for API interactions

## Related Context
- Working on issue #681 to add .egg file removal to scope
- The GitHub MCP server clearly has the code for adding comments but doesn't expose it as a tool

Principle: systems-stewardship

Start by examining the GitHub MCP server's addIssueComment function in /operations/issues.ts and reproduce the missing comment-tool discovery from Claude Code. Trace how operations become exposed MCP tools, then verify that a comment tool is callable and handles the issue-comment request without the gh CLI workaround.

Written by the indexing model from the issue text.