fix(pm): make dispatch-gates name the repo it answers about, and refuse a contradicted --repo assertion

The tool derives gate families from the tree it runs in and never said so.
Handed a sister repo's paths it returned a confident, well-formed, exit-0
answer about the wrong repo, with no tell — and four of the five repos in
scope hold no copy of the script at all, so every sister-repo dispatch was
exposed to it.

Every derivation now opens with a banner naming the repo and commit the
answer came from, and `--repo <owner>/<name>` turns a caller's expectation
into a checked assertion that refuses, naming both repos, on mismatch. Paths
are repo-relative, so a path's home repo is never guessed: the banner is the
unconditional tell and the assertion is the mechanical one. The no-path
merge-base mode is untouched apart from the banner.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MsbKEG4LtERSLaDrbehM3e

Author: claude

.claude/agents/os-dev.md

@@ -137,6 +137,12 @@ JSON,所以终报消息就是 JSON 本身,别无其它。
 半归 PM,在你报告之后读真实门禁 job 结论。⛔ 这不是跳过点名族的许可 —— 它们是你仍然欠的
 便宜一半;你不再欠的是报告前等 CI。
 
+**该脚本只住在 objectstack,答案永远只关于它自己所在的那棵树** —— 每次推导第一行(stderr)
+点名答案取自哪个仓与 commit,读之前先核对。姊妹仓(objectui / cloud)没有 `scripts/pm/`,
+把它们的路径喂到 objectstack 的检出里,得到的是 objectstack 的门禁族:形态完整、退出码
+0、全错;那边的清单从该仓自己的 `package.json` 与 `.github/workflows/` 手工推导。要机械保
+险就加 `--repo <owner>/<name>` 申报本次答案该属于哪个仓 —— 不匹配即拒绝并同时点名两个仓。
+
 **仓级扫描(以 `pnpm lint` = `eslint . --no-inline-config` 扫全仓为首)是 CI 拥有的运
 行,永不是你欠的。** 前台上限之内跑得完就**可以**跑(轻载实测 ~2 分钟;争用下会被 cap
 杀,见「资源纪律」规则 6);默认交付形态是**已证明的收窄**:定向跑受影响文件,并证明这