* test(#3813): pin the #1883 unreadable-milestones contract on the live planning-snapshot path
* fix(#3813): delete the caller-less listMilestoneArchiveDirs seam; #1883 contract now pins the live path
* chore(#3813): changeset fragment (pr number backfilled after PR creation)
* chore(#3813): backfill changeset PR number (4029)
* chore(#3813): docs-exempt marker — internal dead-code removal
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Co-authored-by: sim <sim@local>
