fix(business): 删除保护补齐与单价小数位口径修复（e2e 发现）

- 客户删除保护：被业务引用 → 400（T4 占位注释在业务表就位后漏补，FK 500 暴露）
- 人员删除保护：业务归属（负责/协助）引用纳入检查（同样漏检 500）
- schema 单价类列（DECIMAL 14,4）小数位放行至 4 位：回显 '5000.0000'
  原样提交被两位校验永久拒收（编辑任何带精度单价的历史行都失败）
- 补 2 个集成用例锁定；文案同步「客户归属或业务归属引用」

Co-Authored-By: Claude Code <noreply@anthropic.com>

backend/tests/integration/test_personnel.py

@@ -29,6 +29,7 @@ pytestmark = pytest.mark.integration
 
 _PERSONNEL = "/api/v1/base/personnel"
 _CUSTOMERS = "/api/v1/base/customers"
+_BUSINESSES = "/api/v1/business/businesses"
 
 
 def _uname() -> str:
@@ -234,7 +235,7 @@ class TestDeleteProtection:
         member = _create(client, headers, manager_id=manager["id"])  # 团队成员占用
         blocked = client.delete(f"{_PERSONNEL}/{manager['id']}", headers=headers)
         assert blocked.status_code == 400, blocked.text
-        assert "存在团队成员或客户归属引用，请改为离职而非删除" in blocked.json()["message"]
+        assert "存在团队成员、客户归属或业务归属引用，请改为离职而非删除" in blocked.json()["message"]
 
         client.delete(f"{_PERSONNEL}/{member['id']}", headers=headers)
         freed = client.delete(f"{_PERSONNEL}/{manager['id']}", headers=headers)
@@ -260,7 +261,7 @@ class TestDeleteProtection:
 
         blocked = client.delete(f"{_PERSONNEL}/{owner['id']}", headers=headers)
         assert blocked.status_code == 400, blocked.text
-        assert "存在团队成员或客户归属引用，请改为离职而非删除" in blocked.json()["message"]
+        assert "存在团队成员、客户归属或业务归属引用，请改为离职而非删除" in blocked.json()["message"]
 
         # 保护与在职状态无关：离职并不能让物理删除放行
         client.put(f"{_PERSONNEL}/{owner['id']}/status", json={"status": 0}, headers=headers)
@@ -269,6 +270,55 @@ class TestDeleteProtection:
 
         # 删客户解除引用后方可删人
         assert client.delete(f"{_CUSTOMERS}/{customer['id']}", headers=headers).status_code == 200
+        freed = client.delete(f"{_PERSONNEL}/{owner['id']}", headers=headers)
+        assert freed.status_code == 200, freed.text
+
+    def test_被业务归属引用禁删_负责或协助任一即拦(
+        self, client: TestClient, normal: dict
+    ) -> None:
+        """业务表就位后删除保护补齐：负责/协助引用任一即拦，FK 不以 500 暴露。"""
+        headers = normal["headers"]
+        owner = _create(client, headers)
+        assistant = _create(client, headers)
+        resp_customer = client.post(
+            _CUSTOMERS,
+            json={
+                "company_name": f"t_公司_{uuid.uuid4().hex[:8]}",
+                "owner_name": "张老板",
+                "customer_type": "personal",
+            },
+            headers=headers,
+        )
+        assert resp_customer.status_code == 200, resp_customer.text
+        customer_id = resp_customer.json()["data"]["id"]
+        resp = client.post(
+            _BUSINESSES,
+            json={
+                "customer_id": customer_id,
+                "owner_personnel_id": owner["id"],
+                "assistant_personnel_id": assistant["id"],
+                "items": [
+                    {
+                        "product_name": "t_引用产品",
+                        "product_category": "municipal_water",
+                        "quantity": "1",
+                        "sale_price": "1",
+                    }
+                ],
+            },
+            headers=headers,
+        )
+        assert resp.status_code == 200, resp.text
+
+        for target, label in ((owner, "负责"), (assistant, "协助")):
+            blocked = client.delete(f"{_PERSONNEL}/{target['id']}", headers=headers)
+            assert blocked.status_code == 400, blocked.text
+            assert "业务归属" in blocked.json()["message"], f"{label}引用未拦截"
+
+        # 删除业务解除引用后，人员方可删除（owner 仍被客户归属引用，先删客户）
+        business_id = resp.json()["data"]["id"]
+        assert client.delete(f"{_BUSINESSES}/{business_id}", headers=headers).status_code == 200
+        assert client.delete(f"{_CUSTOMERS}/{customer_id}", headers=headers).status_code == 200
         assert client.delete(f"{_PERSONNEL}/{owner['id']}", headers=headers).status_code == 200