* test(#2631): failing-first planner estimate emission and over-budget surfacing
* feat(#2631): emit plan estimate and surface the over-budget split recommendation
* fix(#2631): extract sizing prose to references to fit planner and plan-phase caps
* fix(#2631): move estimate check to plan-checker; fix template regex and caps
* fix(#2631): restore ALWAYS split literal and keep gsd_run after the launcher preamble
* fix(#2631): invoke estimate-check after the launcher preamble in plan-checker
* fix(#2631): stop double-applying calibration; repair COMMANDS table and stale reference
* chore(#2631): backfill changeset pr to 2670
* chore(#2631): backfill changeset pr to 2670