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/xuanzang/meta.json

@@ -4,18 +4,71 @@
   "tradition": "汉传",
   "school": "法相唯识宗",
   "era": "602-664",
-  "languages": ["zh-classical", "zh", "sa"],
+  "languages": [
+    "zh-classical",
+    "zh",
+    "sa"
+  ],
   "fojin_entity_id": null,
   "sources": [
-    {"type": "cbeta", "id": "T07n0220", "title": "大般若波罗蜜多经"},
-    {"type": "cbeta", "id": "T30n1579", "title": "瑜伽师地论"},
-    {"type": "cbeta", "id": "T31n1585", "title": "成唯识论"},
-    {"type": "cbeta", "id": "T08n0251", "title": "般若波罗蜜多心经"},
-    {"type": "cbeta", "id": "T29n1558", "title": "阿毗达磨俱舍论"},
-    {"type": "cbeta", "id": "T51n2087", "title": "大唐西域记"}
+    {
+      "type": "cbeta",
+      "id": "T07n0220",
+      "title": "大般若波罗蜜多经"
+    },
+    {
+      "type": "cbeta",
+      "id": "T30n1579",
+      "title": "瑜伽师地论"
+    },
+    {
+      "type": "cbeta",
+      "id": "T31n1585",
+      "title": "成唯识论"
+    },
+    {
+      "type": "cbeta",
+      "id": "T08n0251",
+      "title": "般若波罗蜜多心经"
+    },
+    {
+      "type": "cbeta",
+      "id": "T29n1558",
+      "title": "阿毗达磨俱舍论"
+    },
+    {
+      "type": "cbeta",
+      "id": "T51n2087",
+      "title": "大唐西域记"
+    }
   ],
   "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": [
+      "T07n0220",
+      "T30n1579",
+      "T31n1585",
+      "T08n0251"
+    ],
+    "traditions": [
+      "唯识",
+      "法相"
+    ],
+    "dictionary_sources": [
+      "foguang",
+      "dingfubao",
+      "yogacara"
+    ],
+    "keywords": [
+      "唯识",
+      "阿赖耶识",
+      "三性",
+      "五位百法",
+      "因明",
+      "瑜伽"
+    ]
+  }
 }