refactor(zhiyi): v0.3 architecture rebuild — progressive disclosure + provenance + fidelity tests

Sample master (zhiyi) rebuilt to new architecture:
- SKILL.md slimmed from 225→94 lines with decision tree + Quick Ref
- Provenance frontmatter: CBETA IDs, FoJin text IDs, citation_format
- voice.md/teaching.md moved to references/ (loaded on demand)
- sources/ with canonical excerpts (offline-capable)
- tests/fidelity.jsonl: 5 Q&A pairs with expected citations/keywords
- scripts/validate.py: cross-master frontmatter linter
- scripts/test-fidelity.py: Claude API-based fidelity test runner

Follows Anthropic Agent Skills patterns:
  - Progressive disclosure (metadata→body→references)
  - Decision tree for branching workflows
  - Task-gated reference loading
  - Quick Reference table
  - Scripts as black boxes (--help, never Read source)

prebuilt/zhiyi/sources/INDEX.md

@@ -0,0 +1,22 @@
+# 智顗大师 Sources 索引
+
+本目录为离线可用的经文片段，对应本 master 引用的核心经典。
+
+## 收录文件
+
+| 文件 | 来源经典 | CBETA | FoJin | 覆盖主题 |
+|---|---|---|---|---|
+| `mohezhiguan-excerpts.md` | 《摩訶止觀》 | T1911 | [53](https://fojin.app/texts/53) | 一念三千、一心三观、二十五方便、十境十乘、六即佛、圆顿止观 |
+| `fahua-xuanyi-excerpts.md` | 《妙法蓮華經玄義》 | T1716 | [52](https://fojin.app/texts/52) | 五重玄义、五时判教、八教、三谛圆融、开权显实、火宅三车 |
+
+## 引用规范
+
+- 格式：`【《经名》卷N，CBETA_ID】→ https://fojin.app/texts/{fojin_text_id}`
+- 示例：`【《摩訶止觀》卷五上，T1911】→ https://fojin.app/texts/53`
+
+## 说明
+
+- 所有片段节选自 CBETA 公开资料
+- 用于教学引用，不代表完整经义
+- 深入研究请查阅 FoJin 或 CBETA 全本
+- 增补片段欢迎 PR