feat: add search_scope to all teachers + cross-reference tool for inter-teacher dialogue

Each teacher's meta.json now includes search_scope with tradition-specific
CBETA/SuttaCentral IDs, dictionary sources, and keywords for focused RAG
retrieval. New tools/cross_reference.py enables lineage queries and
cross-tradition concept comparison via FoJin KG.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

prebuilt/zhiyi/meta.json

@@ -4,17 +4,66 @@
   "tradition": "汉传",
   "school": "天台宗",
   "era": "538-597",
-  "languages": ["zh-classical", "zh"],
+  "languages": [
+    "zh-classical",
+    "zh"
+  ],
   "fojin_entity_id": null,
   "sources": [
-    {"type": "cbeta", "id": "T46n1911", "title": "摩诃止观"},
-    {"type": "cbeta", "id": "T33n1718", "title": "妙法莲华经玄义"},
-    {"type": "cbeta", "id": "T34n1718", "title": "妙法莲华经文句"},
-    {"type": "cbeta", "id": "T46n1915", "title": "修习止观坐禅法要"},
-    {"type": "cbeta", "id": "T09n0262", "title": "妙法莲华经"}
+    {
+      "type": "cbeta",
+      "id": "T46n1911",
+      "title": "摩诃止观"
+    },
+    {
+      "type": "cbeta",
+      "id": "T33n1718",
+      "title": "妙法莲华经玄义"
+    },
+    {
+      "type": "cbeta",
+      "id": "T34n1718",
+      "title": "妙法莲华经文句"
+    },
+    {
+      "type": "cbeta",
+      "id": "T46n1915",
+      "title": "修习止观坐禅法要"
+    },
+    {
+      "type": "cbeta",
+      "id": "T09n0262",
+      "title": "妙法莲华经"
+    }
   ],
   "version": "1.0.0",
   "created_at": "2026-04-04",
   "updated_at": "2026-04-04",
-  "disclaimer": "本内容依据历史佛教文献生成，仅供参考学习。如需正式修行指导，请亲近善知识。"
+  "disclaimer": "本内容依据历史佛教文献生成，仅供参考学习。如需正式修行指导，请亲近善知识。",
+  "search_scope": {
+    "primary_cbeta_ids": [
+      "T46n1911",
+      "T33n1718",
+      "T34n1718",
+      "T46n1915",
+      "T09n0262"
+    ],
+    "traditions": [
+      "天台",
+      "法华"
+    ],
+    "dictionary_sources": [
+      "foguang",
+      "dingfubao",
+      "tiantai"
+    ],
+    "keywords": [
+      "一念三千",
+      "三谛",
+      "止观",
+      "五时八教",
+      "法华",
+      "圆融"
+    ]
+  }
 }