fix: remove duplicate unity_agents_list tool causing MCP client rejection

The tool was defined twice in editor-tools.js (lines 2411 and 3660).
Duplicate tool names cause the MCP client to silently reject the entire
tool list, making all unity_* tools invisible in Claude Cowork and
Desktop. Removed the older duplicate (and its companion unity_agents_log
which duplicated unity_agent_log).

This is likely the root cause of the MCP tools not appearing for new
users — the server starts and responds correctly, but the client
validation fails on duplicate names.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>