docs: refute finding 15 on measurement

Why: finding 15 proposed merging skill-author and agent-author on the
claim that they share most of contract.md and near-identical steps.
Measured, the pair shares about 150-180 distinct non-blank lines,
against the 2,934 the factory-audit merge removed. ADR-0020's exclusion
of the pair holds, so the merge does not proceed.

Implementation Notes: finding 15 is struck through and carries a dated
Refuted note with per-file counts and the command that reproduces them.
The §7 order and status notes and the §8 ADR-0012 bullet now show no
open finding, with 22 deferred with bin. ADR-0020's rejected
alternative records the measurement; ADR-0025 point 7 no longer calls
the finding open and unmeasured.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/adr/0020-skill-description-and-body-context-contract.md

@@ -535,6 +535,10 @@ Upstream citations below are relative to
   Largest cut available. Rejected because it reopens ADR-0005, ADR-0008 and ADR-0016 together, and a
   merged author skill would carry both the skill-directory scaffold and the dual-provider agent
   scaffold behind one dispatch.
+  **Measured (2026-09-16):** the pair shares about 150–180 distinct non-blank lines — 36 in
+  `contract.md` (of 205 / 126), 13 in `SKILL.md`, 14 in `improve.md`, 48 in the two scaffold
+  scripts — against the 2,934 that the audit-pair merge removed. The rejection holds; simplification
+  audit finding 15 is refuted on this basis.
 - **Demoting Gotchas** to the end of the body or into `references/gotchas.md`, removing its
   position-based exemption from the dispatch rule. Maximum saving on the largest body construct
   (6,830 words, 21% of all body text). Rejected because a gotcha read after the mistake is worthless.