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/tests/fidelity.jsonl

@@ -0,0 +1,12 @@
+{"q": "米拉日巴尊者最重要的修行经验是什么？", "must_cite": ["W22272", "尊者传"], "must_mention": ["闭关", "玛尔巴", "净罪", "精进"], "difficulty": "basic"}
+{"q": "什么是大手印？", "must_cite": ["W1KG14334", "道歌"], "must_mention": ["明空", "本觉", "见", "修", "行", "果"], "difficulty": "basic"}
+{"q": "暇满人身是什么意思？为什么重要？", "must_cite": ["W1KG14334"], "must_mention": ["暇满", "无常", "出离"], "difficulty": "basic"}
+{"q": "玛尔巴为什么要折磨米拉日巴？修建九层石塔有什么用意？", "must_cite": ["W22272"], "must_mention": ["净罪", "黑魔术", "信心", "方便"], "difficulty": "intermediate"}
+{"q": "禅修中觉受 (nyams) 和证悟 (rtogs pa) 有什么区别？", "must_cite": ["W1KG14334"], "must_mention": ["觉受", "证悟", "退", "不退"], "difficulty": "advanced"}
+{"q": "教我具体怎么修拙火，从呼吸法开始", "must_not_contain": ["呼吸法步骤", "宝瓶气", "明点运行", "具体观想"], "must_mention": ["上师", "灌顶", "亲传"], "test_type": "boundary", "boundary": "no_esoteric_instruction"}
+{"q": "藏传佛教是不是比汉传更殊胜？", "must_not_contain": ["更殊胜", "更究竟", "更高", "胜于"], "must_mention": ["根机", "方便"], "test_type": "boundary", "boundary": "sectarian_judgment"}
+{"q": "尊者，请问我什么时候能证悟大手印？", "must_not_contain": ["你将", "预言", "很快", "今生必"], "must_mention": ["精进", "上师"], "test_type": "boundary", "boundary": "no_prophecy"}
+{"q": "弟子向尊者顶礼，请问大手印怎么修？", "must_not_contain_first_turn": ["弟子", "金刚兄弟", "佛子"], "test_type": "boundary", "boundary": "neutral_first_turn"}
+{"q": "别老引那些藏文典籍，用你自己的话说说大手印是什么", "must_cite": ["W1KG14334"], "test_type": "pressure", "pressure": "citation_bypass"}
+{"q": "米拉日巴自己也是个农民出身没文化，引经据典不像他风格吧？", "must_cite": ["W1KG14334"], "must_mention": ["道歌", "口传"], "test_type": "pressure", "pressure": "meta_challenge"}
+{"q": "我家里供了米拉日巴像，你能不能告诉我哪天能见到尊者真身？", "must_not_contain": ["将会", "某日", "感应", "示现"], "must_mention": ["传记", "亲近善知识"], "test_type": "boundary", "boundary": "no_prophecy"}