Controls K1/K2: code and two PREREG amendments, committed before the full run.

simroot/pure.py: flatlagmempt / flatbandmempt / flatflagmempt - A' with only the flat detector
swapped (Lagouanelle without declining outside (0,1), with memory; Chandrupatla's band; none).
A' itself is untouched: bit-identical to the compiled simbracket on all 868 problems (x2).
sweep_controls.py: K2 through sweep_fourth's harness, K1 with the oracle order m*.
Amendment 1: m* <= 0 is undefined (aps.15.22-30, C0.04 crashed the first full attempt).
Amendment 2 (after the smokes; only corpus-level K1 sums and corpus-4 K2 sums were seen): each
side's slope rounded to 0.01, m* defined only when both sides show a zero (jumps C0.03,
aps.15.21), group 'multiple/fractional' = m* >= 2 or m* <= 2/3, the branches of section 8.1
(simple roots measured at 0.99999 fell under the registered 'm* < 1').
tests/test_article_numbers.py: the verifier test runs on Linux only (the paper's numbers are a
Linux run; libm's last digit differs elsewhere, e.g. 4461 vs 4462).

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

tests/test_article_numbers.py

@@ -22,6 +22,10 @@ CREDIT_LABEL = "pure.ratio.derived3.credit"
 
 @pytest.mark.skipif(not os.path.exists(os.path.join(ROOT, "sweep_full.json")),
                     reason="sweep_full.json not present; run sweep_full.py")
+@pytest.mark.skipif(not sys.platform.startswith("linux"),
+                    reason="the paper's numbers come from a Linux run (section 4, Reproducibility); "
+                           "verify_article.py recomputes some of them, and libm's last digit "
+                           "differs on other platforms (e.g. 4461 vs 4462 in Table 1b)")
 def test_every_number_in_the_paper_matches_the_sweep():
     r = subprocess.run([sys.executable, "verify_article.py"], cwd=ROOT,
                        capture_output=True, text=True, timeout=600)