Remove legacy backend routes that no longer have frontend or internal
callers, including the old Claude/Codex MCP APIs, unused Cursor and Codex
helper endpoints, stale TaskMaster detection/next/initialize routes,
and unused command/project helpers.
This reduces duplicated MCP behavior now handled by the provider-based
MCP API, shrinks the exposed backend surface, and removes probe/service
code that only existed for deleted endpoints.
Add an MCP settings API audit document to capture the route-usage
analysis and explain why the legacy MCP endpoints were considered safe
to remove.
