feat(learning-harness): publish every number from the artifacts that produced it

Task 3.8. A number in a roadmap that nobody can regenerate is a claim, not a
measurement. One entry point now writes them all from the committed artifacts
and puts the denominator beside each: how many pairs could be scored, why the
rest could not, which taxonomy version scored them, the noise the family shows
against itself, and what the run cost per pair it got right. Every table says
whether hierarchical partial credit could apply, which today it cannot.

The roadmap section is replaced in place between markers rather than appended,
so the file cannot accumulate a stale number beside a fresh one, and running the
command twice without new artifacts changes nothing. With no baseline recorded
it says so instead of printing an empty table.

The corrected mechanism-lever number travels with the rest: detected five of
seventeen at a negative Youden once only train-split pairs teach, against seven
when every pair taught, with the difference named as what holdout pairs stopped
teaching. Round zero now records what it spent so the cost column has a source.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

tests/test_learning_rounds.py

@@ -188,3 +188,20 @@ def test_an_unscorable_pair_is_listed_and_never_run(tmp_path: Path) -> None:
     assert report.metrics["injection"]["scorable"] == 0
     assert report.metrics["injection"]["unscorable"] == {"identical_twin": 1}
     assert calls == []
+
+
+def test_round_zero_records_what_it_spent(tmp_path: Path) -> None:
+    """Publishing puts a cost beside every number, so the baseline has to know what it cost."""
+    from openultrasast.learning.rounds import run_baseline
+
+    report = run_baseline(
+        [_case(tmp_path, "a")],
+        taxonomy=load_families(),
+        configs_dir=tmp_path / "configs",
+        scan=_steady,
+        model="m",
+        out_dir=tmp_path / "out",
+        spent_usd=lambda: 1.25,
+    )
+    assert report.cost_usd == 1.25
+    assert json.loads((tmp_path / "out" / "baseline" / "m" / "report.json").read_text())["cost_usd"] == 1.25