docs(cli): the new default's K2 digest, measured on the bundle it produces

The default move landed in the previous commit; this is the number it costs a
consumer, measured rather than predicted. `okf build` with no flag over the
43-document reference corpus now yields 517 concepts in 969 files, content
digest `42c8646d...`, `merged + coded rejections = 43 = N`, 817.6 s. The
delivered 2026-09-03 bundle (629 concepts, 1108 files, `9cd74519...`) is
unchanged on disk and reproducing it needs `--outline-run 0 --no-unit-fold`
AND the stamp it was built with -- "the opt-out flags" alone is true and
incomplete, so the report says both.

README and CLAUDE.md now state which two rules are on, what each opt-out is,
and that the proposer's own defaults did not move. One CLAUDE.md sentence was
false as of the move ("a no-flag build stays byte-identical") and is corrected
in place rather than deleted: adding a flag still leaves the default
byte-identical; moving it does not, which is why it took an operator decision.

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

CLAUDE.md

@@ -259,16 +259,32 @@ and fixtures, never code.
   collide); `--ingested-at` and `--proposed-at` default to one shared epoch
   constant rather than the clock, because a wall-clock default takes
   rebuild-equals-incremental away from anyone who omits them.
-  **Six segmentation rules are REACHABLE here and all six are OFF by
-  default** (2026-09-08): `--outline-run N` (Arm D), `--table-grid` (Arm E),
+  **Six segmentation rules are REACHABLE here, and since 2026-09-08 TWO of
+  them are ON by default** -- `--outline-run 3` and `--unit-fold`, the
+  operator's D3 answer (alternative b), each with an explicit opt-out
+  (`--outline-run 0`, `--no-unit-fold`) that together reproduce the pre-move
+  bytes. **The proposer's own defaults did NOT move** (`propose.py`'s rules stay
+  off): the goldens and every published reproduction block are pinned to them,
+  so the two layers disagree on purpose and `cli.DEFAULT_OUTLINE_RUN` /
+  `cli.DEFAULT_UNIT_FOLD` say where. The cost to a consumer is a re-run and it
+  is not small: the 43-document reference corpus goes 629 concepts / 1108 files
+  (`9cd74519...`, the delivered 2026-09-03 tree) to **517 / 969**
+  (`42c8646d...`, default flags, default epoch stamp). **And the number the
+  decision cites belongs to another configuration:** Arm F's 5 of 12 was
+  measured with `--table-grid` ON; without it the same sample scores 2 of 12
+  and `docx` 0 of 3, because the fold's table clause has no joined table to
+  fold. The six (2026-09-08): `--outline-run N` (Arm D), `--table-grid` (Arm E),
   `--unit-fold` (Arm F), `--keep-table-heading` (D1), `--sheet-section-rows`
   and `--drop-wrapped-outline` (both D3), each passed to the proposer
   unchanged. Until that day the build path called the proposer with no
   arm flag at all, so a tender PDF that Arm D splits into nine concepts landed
-  as one -- a build path a full arm behind the proposer. Exposing them is not
-  the same decision as moving one: **which arm should ship as the default is
-  the operator's, and a no-flag build stays byte-identical** (measured by
-  digest before and after, and by Arm E over all 43 corpus documents). Arm C
+  as one -- a build path a full arm behind the proposer. Exposing them was not
+  the same decision as moving one, and the two were taken a session apart:
+  **which arm ships as the default is the operator's**, answered 2026-09-08 as
+  above. Adding a flag still leaves the default byte-identical (measured by
+  digest before and after, and by Arm E over all 43 corpus documents); MOVING
+  the default is the one thing that does not, which is why it took an operator
+  decision and carries an opt-out. Arm C
   (`--max-segment-chars`) stays unexposed: no reference has ever been measured
   for its cap. The two D3 rules read grammars nothing else here reads: a table
   row's FIRST CELL (a run of bare numeric labels cuts the block that holds