Delete autonomous_plan.md (fully shipped), PLAN_playtest.md (all P1-P7
done), PLAN_missions.md and PLAN_leveldesign.md (partial — engine done,
UI polish + 3 final missions + recurring demands + transformer visuals
remain). The surviving TODO list lives in docs/PLAN.md.
Also add the 6-step dev loop to CLAUDE.md (take next topic → implement →
tests → UI test → docs → commit).
