docs(pm-dispatch): name what IS and is NOT build-tier evidence in the fuse

`references/contract-review.md` 〈降档保险丝(机读)〉 said how a seat's own
served tier is READ, and that a self-description is not a reading — it never
said which artefacts are NOT tier evidence. A commit trailer carries a model
string, so a reader who has not seen the AGENTS.md model-free trailer rule
takes it for a tier stamp. That misread once held a PR and cost a withdrawal.

Adds one line under that section carrying both halves: the two admissible
sources for the tier the work was BUILT at (the harness `model` stamps; the
claim's `Container & model:` line) and the exclusion (the `Co-Authored-By`
trailer is a session-attribution constant, never evidence of tier).

The file sits at its ratchet ceiling (60/60, headroom 0), so the added line is
paid by a deletion inside the file — never a re-wrap and never a ceiling raise.
The deleted line is the 外部评审链 bullet in 复核归属与资格, whose rule is
already stated in `SKILL.md` (「外部评审链降为可选事后审计,非放行前提。」) and
whose two named chains are stated in `references/lanes/director.md`, where the
duties of those chains live. The rules-only rewrite convention for this corpus
is one rule per line and no rule already stated in SKILL.md, so the bullet was
a restatement — the ratchet's own header had already classified it as one.

Claude-Session: https://claude.ai/code/session_01MoTv7pn338AZ71owsp19gQ
Co-authored-by: Claude <noreply@anthropic.com>

Author: os-justin

.claude/skills/pm-dispatch/references/contract-review.md

@@ -44,7 +44,6 @@
 - 该命令 0 = 双肢一致且无放宽 tell,4 = 任一不成立,3 = 环境答不了;⛔ 3 不作干净。
 - 放宽 tell 由 `scripts/pm/check-widening-tells.mjs` 判,`no` 撞新键/成员/导出/登记即拒,附 file:line。
 - ③ PR 全部 check 全绿,⛔ 非 required 子集;受管面不适用,draft-only 终局不变。
-- 外部评审链是可选事后审计:分诊定时轮与总监席召唤 ⛔ 不是放行必要条件。
 
 ## 降档保险丝(机读)
 
@@ -54,6 +53,7 @@
 - 保险丝只测座位自会话:`mode:subagent` 里 `get_session` 量的是派发会话,⛔ 不作互证。
 - 传参只是配置 ⛔ 不作达档读数;条款②的 `mode:subagent` 派发恒保留标至席内复核完成。
 - 转录档位核验:采信或清标前 grep 子代理 transcript 中 harness 逐消息盖章的 `model` 字段。
+- 施工档只取 harness `model` 盖章或认领 Container & model 行;`Co-Authored-By` = 署名常量 ⛔ 非证据。
 - 产出裁决的每轮都须读到契约复审档位,见回退证据 ⇒ 裁决整体作废。
 - 父会话只有两个合法动作:逐字采纳,或整体作废(核验失败、越范围、格式不完整)。
 - ⛔ 永不改写、删节或润色子代理裁决。