docs: repair stale TOC anchors in plugins-spec (en + zh-CN) (#7365)

Five table-of-contents links in docs/plugins-spec.md and
docs/plugins-spec.zh-CN.md point at anchors from older heading
wording, so they silently land at the top of the page on GitHub:

- en #10: heading is now "First-party atoms — the atomic pipeline
  plugins assemble"
- zh-CN #3/#10/#13/#19: headings now use fullwidth colon/paren
  punctuation ("兼容性矩阵：…", "一方 atoms：…", "公网 Web 表面（…",
  "为什么这是 OpenDesign 的重要一步"), whose GitHub slugs differ from
  the em-dash/spaced forms the TOC still references

All five now resolve to their sections. Verified with a
github-slugger-compatible anchor audit over the two files plus
`pnpm i18n:check` (P0 core doc links unchanged and green).

docs/plugins-spec.md

@@ -107,7 +107,7 @@ All four scenarios share the same `ApplyResult`, the same run pipeline, and the
 7. [Discovery and install](#7-discovery-and-install)
 8. [The Apply pipeline](#8-the-apply-pipeline)
 9. [Trust and capabilities](#9-trust-and-capabilities)
-10. [First-party atoms](#10-first-party-atoms--open-designs-atomic-capabilities)
+10. [First-party atoms](#10-first-party-atoms--the-atomic-pipeline-plugins-assemble)
 11. [Architecture — what changes in the existing repo](#11-architecture--what-changes-in-the-existing-repo)
 12. [CLI surface](#12-cli-surface)
 13. [Public web surface](#13-public-web-surface-open-designaimarketplace)

docs/plugins-spec.zh-CN.md

@@ -100,23 +100,23 @@ OD 的核心不是「一次 prompt 一次输出」，而是 **long-running desig
 0. [状态](#0-状态)
 1. [愿景](#1-愿景)
 2. [目标与非目标](#2-目标与非目标)
-3. [兼容性矩阵](#3-兼容性矩阵--什么样的文件夹对哪些系统是合法插件)
+3. [兼容性矩阵](#3-兼容性矩阵什么样的文件夹对哪些系统是合法插件)
 4. [插件文件夹形态](#4-插件文件夹形态)
 5. [`open-design.json` schema](#5-open-designjson--schema-v1)
 6. [`open-design-marketplace.json` schema](#6-open-design-marketplacejson--联邦目录)
 7. [发现与安装](#7-发现与安装)
 8. [Apply pipeline](#8-apply-pipeline)
 9. [信任与能力](#9-信任与能力)
-10. [一方 atoms](#10-一方-atoms--open-design-的原子能力)
+10. [一方 atoms](#10-一方-atoms可被插件组装的原子管线)
 11. [架构：现有 repo 要改什么](#11-架构现有-repo-要改什么)
 12. [CLI 表面](#12-cli-表面)
-13. [公网 Web 表面](#13-公网-web-表面-open-designaimarketplace)
+13. [公网 Web 表面](#13-公网-web-表面open-designaimarketplace)
 14. [发布与目录分发](#14-发布与目录分发)
 15. [部署与可移植性：Docker，任意云](#15-部署与可移植性docker任意云)
 16. [分阶段实现计划](#16-分阶段实现计划)
 17. [示例](#17-示例)
 18. [风险与开放问题](#18-风险与开放问题)
-19. [为什么这是 OpenDesign 的重要一步](#19-为什么这是-open-design-的重要一步)
+19. [为什么这是 OpenDesign 的重要一步](#19-为什么这是-opendesign-的重要一步)
 20. [Post-v1 可扩展性：artifact taxonomy、evaluators 与 production handoff](#20-post-v1-可扩展性artifact-taxonomyevaluators-与-production-handoff)
 21. [场景覆盖矩阵与交付路线图](#21-场景覆盖矩阵与交付路线图)
 22. [作者扩展点：基于 v1 substrate 实现未交付场景](#22-作者扩展点基于-v1-substrate-实现未交付场景)