feat: add customer relations API for family and protocols

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/api/basic_info.py

@@ -24,6 +24,7 @@ from app.models.models import (
     BizSampleCode,
     SysUser,
 )
+from app.services.customer_relations import build_customer_relations
 
 router = APIRouter(prefix="/web/admin", tags=["基础信息管理"])
 
@@ -119,6 +120,19 @@ async def list_customers(
     return success_response({"list": result_list, "total": total, "page": page, "pageSize": pageSize, "totalPages": tp})
 
 
+@router.get("/customers/{customer_id}/relations")
+async def get_customer_relations(
+    customer_id: str,
+    user: dict = Depends(require_menu_code("biz:customer:list")),
+    db: Session = Depends(get_db),
+):
+    tenant_no = _get_tenant_no(db, user)
+    data = build_customer_relations(db, customer_id, tenant_no)
+    if not data:
+        return error_response(404, "客户不存在")
+    return success_response(data)
+
+
 @router.post("/customers")
 async def create_customer(
     body: CustomerCreateBody,