docs(pm): narrow the model-identifier rule to content artifacts, with both carve-outs

Two binding instructions read as a conflict for every dispatched dev: the
harness attribution directive mandates a `Co-Authored-By` trailer naming the
serving model on every commit, while the rule the dispatch brief carries
forbids model identifiers in pushed artifacts. Nothing enforced either reading,
so each dev spent a round's deliberation on it and filed the same deviation.

The maintainer ruled it on 2026-09-03: the rule means CONTENT artifacts — PR
titles and bodies, code comments, docs, changesets, issue and PR comments — and
two carve-outs are part of the rule rather than exceptions to it: the
harness-written commit trailer (with its session link), and `.claude/agents/*`
frontmatter `model:`, which `check:agent-model-declared` requires. Devs stop
declaring the deviation.

States it as one bullet in the dispatch-brief construction clauses, beside the
other verbatim clauses a brief carries. No gate over commit messages is added,
per the same ruling.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019RfFHiRCSs3JXLK4cwcfox

Author: claude

.claude/skills/pm-dispatch/references/dispatch-runbook.md

@@ -243,6 +243,9 @@ monitor 按自己的 deadline 触发;身份 = 三元组 `(issue, 分支, PR head
 - **文件面两句原文**:「预期落点是 X;若实测表明真正的生产者在别包,报备后按生产者侧修
   (落点与理由写进报告和 PR 正文),⛔ 不在消费者侧打补丁」—— 只写一个路径名,
   是要求 dev 在守约与修对之间二选一;跨包常等于跨车道,PM 事后补跨座位声明。
+- **模型标识只禁内容工件**(维护者 2026-09-03 裁):PR 标题/正文、代码注释、文档、changeset、
+  issue/PR 评论;两条豁免同属规则 —— harness 写在 commit 的 `Co-Authored-By` 尾注(含 session 链接),
+  与 `.claude/agents/*` frontmatter 的 `model:`(`check:agent-model-declared` 要求);⛔ 不再申报为偏差。
 - **Same-day churn 行与在飞重叠**:派发时 `git log origin/main --oneline -20 -- <paths>`
   见当天合并 ⇒ 加一行「基于合并后的代码工作,issue 引用的片段可能已变,
   先核对当前 main」(dev 的 worktree 切出后不会自己更新)。