test(fixtures): a synthetic K2 denominator for pptx, odt and rtf

`docs/2026-09-04-k2-pptx-odt-rtf.md` measured the corpus denominator for
these three office rows and found it ZERO: `K2/trinn1` holds 43 files and
not one of them is a `pptx`, an `odt` or an `rtf`. So `extract._EVIDENCE`
calls those rows `unmeasured` in the strongest sense available -- they
work by construction and had never met a document at all.

This is the smallest thing that changes that without inventing a corpus.
One authored document -- a title, an intro, a 20-row label/value table, a
caption and a 4x4 grid -- laid out three times in three containers, so
the container and its reader are the only variable between the three
measurements. `k2-office-fasit.json` carries the hand count taken from
the AUTHORED content rather than from any converter's output: 56 cells,
20 pairs, 59 distinct strings, shared by all three. It is committed here,
before the measurement runs, because a fasit written afterwards is a
description of a result rather than a denominator for it.

No converter wrote any of these files. `make_k2_office.py` lays every
part by hand, for the reason `make_fixtures.py` already states and this
set inherits: a file written by the converter and then read by the
converter proves only that the converter agrees with itself, and stays
green through any conversion defect that is symmetric. The commissioning
order offered pandoc as one generator option; the committed fixture
policy forbids it and the policy wins.

Two converter behaviours were measured while laying the RTF out, both of
them structurally plausible input read silently wrong, exit code 0 and no
warning. Without `\pard\intbl` on cell paragraphs, consecutive
`\trowd...\row` rows come back as each row NESTED inside the previous
one: five label/value rows read as five levels of nested table, 2076
characters where 117 were expected. And the `\uN?` unicode escape -- the
form Word emits -- loses the character after it: `A\u248?BC` reads back
as `AoC` with the `B` gone, `A\u248?xBC` reads back as `AoBC`. The
fixture writes `\uN ?` with an explicit space, which round-trips. Neither
is worked around anywhere in `src/`.

The generator and the fasit live one level above `k2-office/` and that is
not tidiness: Door B walks its drop directory recursively, so anything
parked beside the three documents would enter the run and N would stop
being 3.

Three synthetic documents in one house style are not a corpus. The rows
stay `unmeasured` and the suite asserts that they do.

Suite 1132 passed (1127 + 5), `ruff check` and `ruff format --check`
clean.

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

tests/fixtures/README.md

@@ -47,6 +47,56 @@ structurally valid input, silently reduced output, exit code 0 and no warning:
   the xlsx extracts with the sheet name intact and **every cell value gone**.
   The fixture therefore uses a `dimension` element and a shared string table.
 
+## The K2 office fixture set (`k2-office/`)
+
+`krav-presentasjon.pptx`, `krav-tekstdokument.odt` and
+`krav-rikt-tekstformat.rtf` are the synthetic denominator for the three office
+rows the corpus has none of. `docs/2026-09-04-k2-pptx-odt-rtf.md` measured that
+denominator at **zero** — `K2/trinn1` holds 43 files and not one is a `pptx`,
+an `odt` or an `rtf` — so those rows were `unmeasured` in the sense of never
+having met a document at all. Regenerated by `make_k2_office.py` in this
+directory:
+
+```
+python3 tests/fixtures/make_k2_office.py
+```
+
+**One document, three containers.** All three carry the same authored content —
+a title, an intro, a 20-row label/value table, a caption and a 4x4 grid — so
+the only variable between the three measurements is the container and the
+reader that opens it. The counts are hand-counted once, in
+`k2-office-fasit.json`, and shared: **56 cells, 20 pairs, 59 distinct strings.**
+
+**The generator and the fasit live one level up, and that is not tidiness.**
+Door B walks its drop directory recursively, so anything parked inside
+`k2-office/` would enter the run and N would stop being 3.
+
+Same policy as the office fixtures above, for the same reason: every part is
+hand-laid and no converter wrote any of them. The commissioning order offered
+pandoc as a generator option; a file written by the converter and then read by
+the converter would prove only that the converter agrees with itself.
+
+Two things were measured while building this set, both against the vendored
+pandoc 3.9, and both are the house shape — structurally plausible input,
+silently wrong output, exit code 0 and no warning:
+
+- **RTF cell paragraphs need `\pard\intbl`.** Without it, consecutive
+  `\trowd…\row` rows are read as each row NESTED inside the previous one:
+  five label/value rows came back as five levels of nested table, 2076
+  characters where 117 were expected.
+- **The `\uN?` unicode escape loses the character after it.** Measured
+  directly: `A\u248?BC` reads back as `AoC` (ring letter present, `B` gone) and
+  `A\u248?xBC` reads back as `AoBC`. The `?` is taken as the control word's
+  delimiter and `\uc1` then skips a real character. The fixture writes
+  `\uN ?` with an explicit space, which round-trips. **This is the form Word
+  emits**, so it is a converter finding rather than a fixture quirk — recorded
+  in `docs/2026-09-07-k2-pptx-odt-rtf-fixtures.md`, not worked around anywhere
+  in `src/`.
+
+**Three synthetic documents in one house style are not a corpus.** The rows stay
+`unmeasured` in `extract._EVIDENCE` and `tests/test_k2_office_fixtures.py`
+asserts that they do.
+
 ## The proposer's default-profile golden
 
 `propose-golden-default.json` is the artifact `tools/okf_propose_segments.py`