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/fazang/meta.json

@@ -4,17 +4,64 @@
   "tradition": "汉传",
   "school": "华严宗",
   "era": "643-712",
-  "languages": ["zh-classical", "zh"],
+  "languages": [
+    "zh-classical",
+    "zh"
+  ],
   "fojin_entity_id": null,
   "sources": [
-    {"type": "cbeta", "id": "T10n0279", "title": "大方广佛华严经(八十华严)"},
-    {"type": "cbeta", "id": "T35n1733", "title": "华严经探玄记"},
-    {"type": "cbeta", "id": "T45n1866", "title": "华严一乘教义分齐章"},
-    {"type": "cbeta", "id": "T45n1875", "title": "华严经义海百门"},
-    {"type": "cbeta", "id": "T45n1876", "title": "修华严奥旨妄尽还源观"}
+    {
+      "type": "cbeta",
+      "id": "T10n0279",
+      "title": "大方广佛华严经(八十华严)"
+    },
+    {
+      "type": "cbeta",
+      "id": "T35n1733",
+      "title": "华严经探玄记"
+    },
+    {
+      "type": "cbeta",
+      "id": "T45n1866",
+      "title": "华严一乘教义分齐章"
+    },
+    {
+      "type": "cbeta",
+      "id": "T45n1875",
+      "title": "华严经义海百门"
+    },
+    {
+      "type": "cbeta",
+      "id": "T45n1876",
+      "title": "修华严奥旨妄尽还源观"
+    }
   ],
   "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": [
+      "T10n0279",
+      "T35n1733",
+      "T45n1866",
+      "T45n1875",
+      "T45n1876"
+    ],
+    "traditions": [
+      "华严"
+    ],
+    "dictionary_sources": [
+      "foguang",
+      "dingfubao"
+    ],
+    "keywords": [
+      "法界",
+      "华严",
+      "十玄",
+      "六相",
+      "事事无碍",
+      "因陀罗网"
+    ]
+  }
 }