feat(propose,consume,tools): the type that declares nothing, and the prefix that is not a word

Three of round 9's four measured holes, each closed with a rule chosen on a
measurement rather than named as a limit.

`rtf` GIVES 0 SEGMENTS -> 6 of 6 AUTHORED TITLES over N = 4. The container has
no heading style, so the author's title is bold text. The grammar is markdown,
not `rtf`: the converter already writes that title as `**...**` in the same
output every office row produces, so no `rtf`-only heading form exists. Three
parameters were swept over 47 readable documents and ONE carried -- refusing a
line that ends in terminal punctuation takes false-positive lines from 9-12 to
1-2. A maximum title length (unlimited/40/60/80/120) and a
must-stand-between-blank-lines clause are both FLAT, so neither is in the rule.
The last false positive is closed by G1, the principle `_gate_outline` already
carries: recovery yields to declaration. False positives are then 0 of the 31
declaring documents by construction, and 0 of 27 on the corpus. Reach: 2 of 39
corpus documents, both `docx`, 0 of 33 `pdf` and 0 of 2 `xlsx`. Behind
`--bold-title`, default OFF pending the hit@8 measurement; the default bundle
is byte-identical without it.

BOTH ALTERNATIVES THE ORDER NAMED WERE MEASURED AND FELLED. A fourth hand-laid
fixture DECLARES heading styles in a stylesheet and the converter discards
them, emitting the same bold line -- so "read the declared headings out of the
markdown" has nothing to read. `rtf` -> `docx` -> markdown yields 0 ATX
headings on that same document, because the loss is in the `rtf` READER before
any writer sees the style. Fixtures are hand-laid in `make_k2_office.py` with
the fasit written first; they live in their own directory because Door B walks
a drop directory recursively and `k2-office/` reads its N off the listing.

THE PREFIX OVER-MATCH: THREE CANDIDATES MEASURED, ALL THREE FAILED ON ONE ROW.
Re-measured on the pinned 453-concept bundle with the control run first:
`under` occurs 79 times by equality and matches 172 by prefix, `undersjoisk` 0
and 172, `bilateral` 0 and 400 of 453, `standhaftig` 0 and 219. The two extra
known-negatives were FOUND, not chosen -- every 4-character prefix ranked by
document frequency, then a real word taken from the widest. A longer floor
(5-8), a coverage share (0.5-0.8) and a long-words-only floor (>= 8) each cost
row 1 its rank on the default bundle and the whole row on Arm B. Decomposed:
row 1's token `prisene` reaches its gold document through
`pris|sammenstilling` on four characters -- 0.57 of one word and 0.22 of the
other -- so the over-match and the wanted match are one mechanism.

THE FOURTH CANDIDATE IS THE ANSWER: the shared prefix must be a WORD the bundle
uses. `pris` is; `bila` and `stan` are not. `bilateral` 400 -> 0 and 512 -> 0,
`standhaftig` 219 -> 56 and 235 -> 33, every hit@8 row keeping rank 1 on BOTH
bundles. `undersjoisk` stops at 162 because `under` IS a word here -- a genuine
Norwegian morpheme, so that residual is a different answer, not a ceiling. ON
by default (`--no-stem-prefix`), pinned with its own known-negative on the
shipped bytes.

THE SHIM: a path importer holds the object `module_from_spec` made, and
`sys.modules[__name__] = _impl` never reaches it. Measured under both counting
methods -- 3 of 76 public names by `vars()`. One line copies the public names
into this file's globals; the dunder filter is load-bearing, because an
unfiltered copy overwrites `__name__` before the next line uses it as the alias
key. It restores attribute ACCESS and not patch-through, which is why the alias
stays. A CHANGELOG note under 0.7.0 and a shim docstring line say so, since
what the consumer asked for was the note.

Suite 1515 -> 1535.

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

tests/fixtures/k2-rtf-variants/krav-rikt-tekstformat-fet-alene.rtf

@@ -0,0 +1,5 @@
+{\rtf1\ansi\ansicpg1252\deff0{\fonttbl{\f0\froman Times New Roman;}}\pard\sa180\b Kravspesifikasjon for tunnelbelysning\b0\par
+\pard\sa180 Dokumentet samler kravene til belysning i vegtunneler over 500 meter.\par
+\pard\sa180\b Luminanskrav per trafikklasse\b0\par
+\pard\sa180 Terskelluminansen er 145 candela og gjelder i hele overgangssonen.\par
+}

tests/fixtures/k2-rtf-variants/krav-rikt-tekstformat-fet-i-avsnitt.rtf

@@ -0,0 +1,4 @@
+{\rtf1\ansi\ansicpg1252\deff0{\fonttbl{\f0\froman Times New Roman;}}\pard\sa180\b Kravspesifikasjon for tunnelbelysning\b0\par
+\pard\sa180 Dokumentet samler kravene til belysning i vegtunneler over 500 meter.\par
+\pard\sa180 Avvik fra kravene krever soknad om \b fravik\b0  fra byggherren for arbeidet starter.\par
+}

tests/fixtures/k2-rtf-variants/krav-rikt-tekstformat-stil.rtf

@@ -0,0 +1,5 @@
+{\rtf1\ansi\ansicpg1252\deff0{\fonttbl{\f0\froman Times New Roman;}}{\stylesheet{\s0 Normal;}{\s1\b\fs32 heading 1;}{\s2\b\fs28 heading 2;}}\pard\s1\b\fs32 Kravspesifikasjon for tunnelbelysning\b0\fs24\par
+\pard\s0\sa180 Dokumentet samler kravene til belysning i vegtunneler over 500 meter.\par
+\pard\s2\b\fs28 Luminanskrav per trafikklasse\b0\fs24\par
+\pard\s0\sa180 Terskelluminansen er 145 candela og gjelder i hele overgangssonen.\par
+}