Record the user-reported Arch X11 validation pass and thread it through the portable and runtime validation matrices.
Adjust the milestone 2 and 3 closeout wording so one fully validated representative distro family is enough for now, while keeping Debian/Ubuntu, Fedora, and openSUSE coverage as an explicit milestone 5 GA signoff requirement.
Update the roadmap and GA validation rollup to mark milestones 2 and 3 complete for now rather than fully GA-complete, and archive the raw Arch evidence in user-readiness/1773357669.md.
Validation: documentation consistency review only; no code or behavior changes were made.
