docs: 品牌全量口径统一为「南方基金」+ 作废文档清理

1) 客服 Agent 四份交付文档 + 构建脚手架：品牌由包装占位 XX科技 / 旧名 南方财富
   统一为南方基金（热线 400-889-8899 / 官网 nffund.com），系统名改为「智能服务系统」；
   同步追加 §0.4 修订记录行，工程记录行保留原占位字面以支撑硬编码扫描验收。
2) 开发文档：清理 28 份已作废/残留文档（14 份移出归档 + 14 份仓库副本），
   新增《文档规整方案与开发前待决事项-2026-09-17》。
3) 客服agent 四份交付文档首次纳入本分支。

app/service/offsite_nl2sql_adapter.py

@@ -0,0 +1,76 @@
+"""场外基金专用 NL2SQL 适配器。"""
+
+from importlib import import_module
+from typing import cast
+
+from sqlalchemy import create_engine
+from sqlalchemy.engine import Engine
+
+from app.core.config import Settings, get_settings
+from app.core.contracts import RequestContext
+
+
+class OffsiteNl2SqlAdapter:
+    """把场外基金上下文转换为 query_dict 的稳定参数并执行只读查询。"""
+
+    script_path = "nl2sql_yc.py"
+
+    def __init__(
+        self,
+        db_engine: Engine | None = None,
+        settings: Settings | None = None,
+    ) -> None:
+        self._db_engine = db_engine
+        self._settings = settings or get_settings()
+        self._owns_engine = db_engine is None
+
+    def query(self, question: str, context: RequestContext) -> dict[str, object]:
+        try:
+            query_dict = getattr(import_module("nl2sql_yc"), "query_dict", None)
+            if not callable(query_dict):
+                return {"status": "error", "message": "NL2SQL入口query_dict不存在"}
+            db_engine = self._get_db_engine()
+            result = cast(dict[str, object], query_dict(
+                question,
+                self._auth_context(context),
+                db_engine=db_engine,
+                use_llm=False,
+                persist_audit=False,
+            ))
+            if isinstance(result, dict):
+                return result
+            return {"status": "error", "message": "NL2SQL返回格式不正确"}
+        except (OSError, RuntimeError, ValueError) as exc:
+            return {"status": "error", "message": f"NL2SQL调用失败：{type(exc).__name__}"}
+
+    def close(self) -> None:
+        """释放适配器自行创建的同步连接池。"""
+        if self._owns_engine and self._db_engine is not None:
+            self._db_engine.dispose()
+            self._db_engine = None
+
+    def _get_db_engine(self) -> Engine:
+        if self._db_engine is not None:
+            return self._db_engine
+        dsn = self._settings.mysql_dsn
+        if dsn.startswith("mysql+asyncmy://"):
+            dsn = dsn.replace("mysql+asyncmy://", "mysql+pymysql://", 1)
+        elif dsn.startswith("mysql://"):
+            dsn = dsn.replace("mysql://", "mysql+pymysql://", 1)
+        if not dsn:
+            raise RuntimeError("未配置数据库连接")
+        self._db_engine = create_engine(dsn, pool_pre_ping=True)
+        return self._db_engine
+
+    @staticmethod
+    def _auth_context(context: RequestContext) -> dict[str, object]:
+        return {
+            "user_id": int(context.user_id) if context.user_id.isdigit() else None,
+            "roles": list(context.roles),
+            "allowed_domains": ["market_nav", "trading_account", "product_fee"],
+            "customer_scope": context.data_scope if context.data_scope in {
+                "self", "own_customers", "all",
+            } else "all",
+            "max_rows": 100,
+            "max_query_seconds": 10,
+        }