feat: expand to Tibetan + Theravada — 10 masters across 三大传统 (v0.4)

Adds the project's first non-Chinese masters, taking the scope from
"Chinese Buddhist" to "Buddhist" and matching the project name's
broader implication.

New masters
-----------
• prebuilt/milarepa — Tibetan Kagyu yogi (1052–1135). Sources:
  The Hundred Thousand Songs of Milarepa (mGur 'bum, BDRC W1KG14334)
  and The Life of Milarepa (rNam thar, BDRC W22272). Coverage:
  Mahāmudrā view, Naro Chodruk (name-level only — no esoteric steps),
  retreat & austerity, guru yoga, karma & purification.

• prebuilt/ajahn-chah — Thai Forest Tradition founder of Wat Pah Pong
  (1918–1992). Sources: Pali Canon (SuttaCentral SC IDs) plus
  authorized English collections Food for the Heart, A Still Forest
  Pool, Living Dhamma. Coverage: sati & satipaṭṭhāna, ānāpānasati,
  three characteristics, letting go, sīla-samādhi-paññā, middle way.

HARD-GATE additions
-------------------
• no_esoteric_instruction — Tibetan tantric practice steps (tummo,
  generation/completion stages, empowerment-required visualizations
  and mantras) are never disclosed; queries are redirected to
  qualified teachers. Boundary registered in
  scripts/validate-fidelity.py.

• No fabricated quotes for Theravāda discourses — Ajahn Chah quotes
  must trace to authorized publications; no synthesized "Ajahn Chah
  said" dialogue.

Citation system
---------------
BDRC:Wxxxxx (Tibetan canon) and SuttaCentral SC IDs are now
first-class alongside CBETA Txxnxxxx in frontmatter sources lists.
validate.py already accepts non-cbeta sources via the existing
title-or-cbeta_id check, no schema change required.

Cross-tradition compare-masters mappings
----------------------------------------
prebuilt/compare/SKILL.md gets new fallback rows for: 苦行/闭关
(xuyun + milarepa), 正念/觉知 (huineng + ajahn-chah + xuyun),
出离心/无常 (yinguang + milarepa + ajahn-chah), 三大传统对比
(huineng + milarepa + ajahn-chah), and adds milarepa to 般若/空性,
ajahn-chah to 戒律/行持.

Surface updates
---------------
• Description across package.json, .claude-plugin/{plugin,marketplace}.json,
  .cursor-plugin/plugin.json: "Chinese Buddhist" → "Buddhist",
  "8 prebuilt masters" → "10 prebuilt masters across 汉传/藏传/南传".
• README.md + README_EN.md: cross-tradition rows in the situational
  guidance table; new master cards for Milarepa and Ajahn Chah with
  appropriate provenance notes; v0.4 release banner replaces v0.3.
• SKILL.md preset list reorganized by tradition.
• CHANGELOG.md gets a [0.4.0] section.
• package.json keywords add tibetan-buddhism, theravada, bdrc,
  suttacentral.

Validation
----------
• python scripts/validate.py --strict → ✅ 11 masters pass
• python scripts/validate-fidelity.py → ✅ 11 masters validated
  (12 + 13 fidelity cases for the two new masters)
• python scripts/test-fidelity.py --all --dry-run → ✅
• pytest tests/ → ✅ 31 passed, 6 skipped

The progressive-disclosure shape of v0.3 is preserved exactly, so
the fidelity-smoke CI cost cap is unchanged.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

prebuilt/milarepa/meta.json

@@ -0,0 +1,83 @@
+{
+  "name": "米拉日巴",
+  "name_tib": "མི་ལ་རས་པ",
+  "name_wylie": "mi la ras pa",
+  "slug": "milarepa",
+  "tradition": "藏传",
+  "school": "噶举派（香巴噶举 / 达波噶举）",
+  "era": "1052-1135",
+  "languages": [
+    "bo",
+    "zh",
+    "en"
+  ],
+  "fojin_entity_id": null,
+  "sources": [
+    {
+      "type": "tibetan_canon",
+      "id": "BDRC:W1KG14334",
+      "title": "米拉日巴道歌集（十万歌集，mGur 'bum）"
+    },
+    {
+      "type": "tibetan_canon",
+      "id": "BDRC:W22272",
+      "title": "密勒日巴尊者传（rNam thar）"
+    }
+  ],
+  "version": "1.0.0",
+  "created_at": "2026-05-02",
+  "updated_at": "2026-05-02",
+  "disclaimer": "本内容依据藏传佛教文献生成，仅供参考学习。如需正式修行指导，请亲近具格上师。",
+  "search_scope": {
+    "primary_source_ids": [
+      "BDRC:W1KG14334",
+      "BDRC:W22272"
+    ],
+    "traditions": [
+      "噶举",
+      "大手印",
+      "那洛六法"
+    ],
+    "dictionary_sources": [
+      "rangjung_yeshe",
+      "84000_glossary"
+    ],
+    "keywords": [
+      "大手印",
+      "phyag chen",
+      "明空双运",
+      "拙火",
+      "tummo",
+      "那洛六法",
+      "naro chodruk",
+      "苦行",
+      "山中闭关",
+      "道歌",
+      "mgur",
+      "上师瑜伽",
+      "guru yoga",
+      "玛尔巴",
+      "Marpa",
+      "禅定觉受",
+      "nyams",
+      "证悟",
+      "rtogs pa",
+      "无常",
+      "暇满",
+      "出离",
+      "菩提心",
+      "空性",
+      "stong nyid",
+      "本觉",
+      "rig pa",
+      "中阴",
+      "bardo",
+      "气脉明点",
+      "rtsa rlung thig le",
+      "因果",
+      "业",
+      "黑魔术忏悔",
+      "猎人贡波多杰"
+    ]
+  }
+}