docs: general wording for the example-base document counts

Replace the exact document counts of earlier example bases (and the
per-base counts in the sources-format note) with general wording or
N-of-N in prose, comments and docstrings. Percentages and numerators
stay; no constant, assertion or test data changes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -880,12 +880,12 @@ when the seam is detached, so the loop cannot silently degrade into theater.
 - **An identifier that stands everywhere identifies nothing (P18).** The validator's stage 0b
   grounds each proposed cost code in the run's non-model-authored input. Plain containment was not
   enough: measured on a live run, a proposal put 250 000 NOK on a line coded with the knowledge
-  base's own *name*, carried by all 2 756 of its documents — and the whole gate said `validated`.
+  base's own *name*, carried by every one of its documents — and the whole gate said `validated`.
   A code now grounds only if it is at least 3 characters long **and** appears in fewer than 5 % of
   the documents the input is made of, with an absolute floor of 10 documents so the share is never
   taken over a handful. Both numbers are measured, not chosen: across the four delivered corpora no
   code-shaped token of 1 692 distinct ones reaches 5 % (highest 1.35 %), and the shortest real
-  identifier is 4 characters. The refusal names the denominator — "appears in 2 756 of the 2 756
+  identifier is 4 characters. The refusal names the denominator — "appears in N of the N
   documents this run was given" — because that reason is fed verbatim into the next attempt's
   prompt. A caller that declares no document boundaries is unchanged by construction: one document
   can never reach the floor.