chore(ruff): the acceptance was whatever the default happened to be [skip-docs]

`uv sync --frozen` resolved ruff 0.15.22 and the tree read clean. A loose
install resolves 0.16.6, under which the SAME untouched code reports 148
findings -- 4 more than round 9 counted, because this round added four files.
All of them are new rules rather than new defects: 0.16 widened the default
rule set to whole families (YTT, ASYNC, PL, ISC, C4, UP, B, SIM, FURB, ...).

(`[skip-docs]` is for CLAUDE.md, which a lint-configuration change does not
reach. README's developer section IS updated in this commit.)

THE DEFECT IS NOT THE 148, IT IS THAT NOBODY CHOSE THEM. `[tool.ruff]` set only
`line-length` and `target-version`, so the acceptance was ruff's default, and
the tree stayed green only as long as the lockfile froze an old ruff. `select`
is now written down: `E4`, `E7`, `E9`, `F` (the historical default), `I`
because this tree already keeps imports sorted, and `RUF100` so a `noqa` that
has stopped meaning anything is caught rather than left as decoration. Pin
`ruff>=0.9` -> `ruff>=0.16.6,<0.17`.

Per rule, before -> after: RUF100 50 -> 0, I001 20 -> 0, ISC004 19, PLW1510 8,
C408 8, EXE001 6, RUF007 5, PLE2515 4, UP031 3, B017 3, and fourteen more with
2 or fewer -- the families out of the declared set are 0 by selection, and 148
is the number to start from if they are adopted, which is a separate decision
and not one to take inside a version-pin commit. 57 were auto-fixed; one E402
was reintroduced by the import-sorting fix merging a block away from its
`noqa`, and got the directive back rather than a bare one.

`S` IS MEASURED OUT, NOT ASSUMED OUT: it reports 2657 `S101` on a suite whose
every assertion is an `assert`, and `S603` flags 19 subprocess calls of which
one was ever marked -- selecting it buys 18 suppressions and no defect. Two
`noqa` directives naming non-selected rules were dropped with that reason
recorded in the configuration instead.

THE TWO FILES 0.16 WOULD REFORMAT ARE MARKDOWN, NOT PYTHON: `README.md` and
`docs/2026-09-08-blindsone-below-k-k2.md`. 0.16 formats fenced Python inside
markdown, and both blocks are RECORDS -- the second is a quotation of
`COST_VOCABULARY` as it stood when that measurement was taken. Reformatting a
quotation makes it stop being one, so markdown is excluded from the formatter
and `ruff format --check .` stays in the acceptance over `.py`.

`tools/okf_consume_measure.py` is fenced by the order as run-not-edited, so its
three findings are exempted by path with the reason and the debt named, and its
bytes are untouched.

THE LOCKFILE TRAP IS CLOSED, NOT AVOIDED. `uv.lock` predated the `[ocr]` extra,
so any unlocked resolve wrote that extra's transitive tree back into it -- 681
insertions over 4 deletions, twice now, and round 9 recorded the cause as
`uv run` OUTSIDE the project when it is `uv run` without `--frozen` INSIDE it.
The relock is complete for every declared extra (703 insertions, 26 deletions),
and measured after it, an unfrozen `uv run` leaves the file alone.

`ruff check src tests tools`, `ruff format --check .` (0.16.6), `mypy src` over
21 files and 1535 tests, all green.

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

tools/okf_contract_check.py

@@ -20,7 +20,7 @@ from pathlib import Path
 
 sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "src"))
 
-from llm_ingestion_okf import contract_check as _impl  # noqa: E402
+from llm_ingestion_okf import contract_check as _impl
 
 if __name__ == "__main__":
     raise SystemExit(_impl.main())