Planner fix from neatlogs Investigate: copy commands only, guard against invented steps

The neatlogs detection "planner invented a step" flagged the planner spans of 3 v1 runs. neatlogs Investigate traced it to the planner prompt and proposed a stricter one (evidence/neatlogs-investigation.md). This applies it and adds code guards that drop no-op, invented and fake-secret steps, plus a plan cache so the same page gives the same plan.