feat(accounting): okf build accounts for every source element

okf build --accounting PATH inventories every source document before
extraction, in the gate's per-format vocabulary, and after the run gives
each element one fate (carried / pointer / coded rejection), written as
JSON and summarised in log.md. "carried" is checked against the written
concept bodies, so a gate that drops a line is found (test). Exit 1 on
anything unaccounted or double-booked. Opt-in: +744 s (+19 %) on the
43-document reference corpus, and that corpus fails the check on 24 real
losses (22 images on text-less PDF pages, 2 docx Title paragraphs).

Changed without the flag:
- okf build exits 1 when it extracted documents and persisted none.
  Door B and corpus.measure are unchanged. One test relied on exit 0.
- An image file carried through a persisted document is its own K1b
  column, no longer also extractor_unknown. The set is what the resolver
  actually carried (ExtractedDocument.files), never a byte match.

tools/okf_accounting_gate.py (checks untouched) is green on all six rows,
R761 110 of 110 under both gates.

Report: docs/2026-09-17-innholdsregnskapet-bygget.md

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

tests/test_accounting_gate.py

@@ -1,7 +1,7 @@
 """The content-accounting gate's own tests (`tools/okf_accounting_gate.py`).
 
-The gate is RED today by design: `okf build` has no source inventory and no
-per-element accounting. These tests are GREEN and prove three things.
+The gate was written RED at `0b00de4`, before `okf build` had a source
+inventory or a per-element account. These tests are GREEN and prove three things.
 
 1. The fasit is independent. `tools/okf_witness.py` imports no
    `llm_ingestion_okf` module -- checked on the live import graph of a process
@@ -10,9 +10,11 @@ per-element accounting. These tests are GREEN and prove three things.
    again to hand counts on four documents.
 2. Every row CAN turn green and CAN turn red, each boundary driven from both
    sides with synthetic build output (the door the capability must open).
-3. Run against the real `okf build` at this commit, the gate sees the three
-   defects it was ordered for: no inventory, a file carried AND rejected, and
-   a rejected document logged as "0 carried of 0 found".
+3. Run against the real `okf build`, the fixture rows are green. They were
+   red at `0b00de4` on the three defects the gate was ordered for (no
+   inventory, a file carried AND rejected, a rejected document logged as "0
+   carried of 0 found"); `test_a_file_carried_through_a_document_and_rejected_
+   is_double_booked` and the row 4 tests keep those defects detectable.
 """
 
 from __future__ import annotations
@@ -395,31 +397,23 @@ def test_bad_usage_exits_two() -> None:
 def real_rows() -> list[gate.Row]:
     pytest.importorskip("pdfplumber")
     pytest.importorskip("pypandoc")
-    if gate.door_available():
-        pytest.skip("the accounting door exists; these rows describe the build before it")
     return gate.evaluate(r761=None, ci=True, consume=False)
 
 
-def test_the_real_gate_is_red_on_rows_two_three_and_four(real_rows: list[gate.Row]) -> None:
-    assert [r.number for r in real_rows if r.fails] == [2, 3, 4]
-    assert [(r.number, r.status) for r in real_rows if not r.fails] == [
+def test_the_door_exists() -> None:
+    assert gate.door_available()
+
+
+def test_the_real_gate_is_green_on_every_fixture_row(real_rows: list[gate.Row]) -> None:
+    """Rows 1-5 against the real `okf build`; row 6 needs R761 and is skipped
+    here. Written red at 0b00de4 (rows 2, 3, 4 red), green once the build
+    accounts for every element."""
+    assert [(r.number, r.status) for r in real_rows] == [
         (1, gate.GREEN),
+        (2, gate.GREEN),
+        (3, gate.GREEN),
+        (4, gate.GREEN),
         (5, gate.GREEN),
         (6, gate.SKIPPED),
     ]
-
-
-def test_the_real_gate_sees_the_graphics_carried_and_rejected(real_rows: list[gate.Row]) -> None:
-    row3 = real_rows[2]
-    assert "d = 2 double-booked" in row3.reason
-    doubled = [d for d in row3.details if "AND rejected" in d]
-    assert [d.split(":")[0] for d in doubled] == [
-        "file graphics/figur-84-1.png",
-        "file graphics/tabell-84-2.png",
-    ]
-
-
-def test_the_real_gate_sees_the_rejected_document_logged_as_empty(
-    real_rows: list[gate.Row],
-) -> None:
-    assert "log says 0 carried of 0 found; the source declares 1" in "\n".join(real_rows[3].details)
+    assert real_rows[2].reason.startswith("u = 0 unaccounted, d = 0 double-booked")