fix: address review — consistent evidence fields, unstake all positions

- Evidence file: change result to PENDING (not INCREASED) with delta_bps 0,
  since this is a registration placeholder, not a measured run
- Attack file: add missing unstake for position 6 so all staking positions
  are cleaned up

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

onchain/script/backtesting/attacks/floor-ratchet-oscillation.jsonl

@@ -50,4 +50,5 @@
 {"op":"mine","blocks":50}
 {"op":"buy_recenter_loop","count":20,"amount":"100000000000000000000"}
 {"op":"unstake","positionId":5}
+{"op":"unstake","positionId":6}
 {"op":"sell","amount":"all","token":"KRK"}