chore(api): remove unused backend endpoints after MCP audit

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.

src/utils/api.js

@@ -99,11 +99,6 @@ export const api = {
     if (token) params.set('token', token);
     return `/api/search/conversations?${params.toString()}`;
   },
-  createProject: (path) =>
-    authenticatedFetch('/api/projects/create', {
-      method: 'POST',
-      body: JSON.stringify({ path }),
-    }),
   createWorkspace: (workspaceData) =>
     authenticatedFetch('/api/projects/create-workspace', {
       method: 'POST',