v2.1.0 — `mcp --expose` options; the account is the boundary

vmware-monitor mcp accepts the family's new --expose / --allow-write options (vmware-policy 1.20.0). This server has
no write tools, so --expose read offers the same tools as the default; the options exist so every server in the
family can be started the same way. references/setup-guide.md now says why the service account must itself be
read-only: an agent with a shell can reach the platform without this skill. Requires vmware-policy>=1.20.0.