item 21 McNemar scored: drop-bucket edge significant (2:6 p=0.0094, survives Bonferroni x4); overall A-vs-B ns; + session handoff, fig cleanup

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/mcnemar_carrycot.py

@@ -22,5 +22,8 @@ for cell in ("2:2", "2:6"):
              if star.get(i) == "drop" and a[i] and not b[i])
     dy = sum(1 for i in ids
              if star.get(i) == "drop" and b[i] and not a[i])
+    dn = dx + dy
+    dp = (min(1, sum(comb(dn, k) for k in range(max(dx, dy), dn + 1))
+              / 2 ** dn * 2) if dn else 1)
     print(f"{cell}: carry-only={x} ff-only={y}  McNemar p={p:.4f}  "
-          f"drop-bucket discordants {dx}-{dy}")
+          f"drop-bucket discordants {dx}-{dy} McNemar p={dp:.4f}")