feat(calc): 二次分摊拆行与 #12 单笔侧开关——按方案比例拆给参与人、余额归负责人

- _personal_rate 的 TPL_MANAGER_SHARE 分支读 manager.personal.included：1=按业务员递减公式计提，0=单笔落 0（现状）
- _load_allocations 装载生效方案并防御拦截（合计超 100%、参与人含负责人）
- _persist_ledger 拆行落库：参与人=份额×比例(q2)、负责人=q2 全额−已分累计（行合计守恒防分漂）；快照带 alloc_plan/alloc_role/alloc_ratio
- _prepare_mode 重算改 list_active_by_receipt 作废全部拆分行；uk 三列版支持同回款按人多行
- business_service 保存侧同口径校验（超 100% 400、负责人自分 400、hint 文案定稿）
- 集成用例 +5（拆行守恒/叠加进度登记/重算全作废/双拦截）+保存侧 3 条

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

backend/tests/integration/test_businesses.py

@@ -412,6 +412,71 @@ class TestEdit:
         assert len(detail["items"]) == 1
         assert Decimal(detail["items"][0]["quantity"]) == Decimal("100")
 
+    def test_二次分配方案合计超100_保存400(self, client: TestClient, normal: dict) -> None:
+        """口径（澄清 #1/#2 答复 2026-10-19）：分配绩效、余额归合同负责人——
+        超 100% 会把负责人份额算成负数，保存侧先拦（核算侧另有防御）。"""
+        headers = normal["headers"]
+        customer = _customer(client, headers)
+        owner = _personnel(client, headers)
+        part = _personnel(client, headers)
+        data = _create(client, headers, customer["id"], owner_personnel_id=owner["id"])
+
+        resp = client.put(
+            f"{_BUSINESSES}/{data['id']}",
+            json=_payload(
+                customer["id"],
+                secondary_allocations=[
+                    {"personnel_id": part["id"], "ratio": "60"},
+                    {"personnel_id": _personnel(client, headers)["id"], "ratio": "50"},
+                ],
+            ),
+            headers=headers,
+        )
+        assert resp.status_code == 400, resp.text
+        assert "超过 100%" in resp.json()["message"]
+
+    def test_二次分配参与人含负责人_保存400(self, client: TestClient, normal: dict) -> None:
+        headers = normal["headers"]
+        customer = _customer(client, headers)
+        owner = _personnel(client, headers)
+        data = _create(client, headers, customer["id"], owner_personnel_id=owner["id"])
+
+        resp = client.put(
+            f"{_BUSINESSES}/{data['id']}",
+            json=_payload(
+                customer["id"],
+                secondary_allocations=[{"personnel_id": owner["id"], "ratio": "30"}],
+            ),
+            headers=headers,
+        )
+        assert resp.status_code == 400, resp.text
+        assert "含合同负责营销人员" in resp.json()["message"]
+
+    def test_二次分配方案合法比例_保存成功且回显(
+        self, client: TestClient, normal: dict
+    ) -> None:
+        headers = normal["headers"]
+        customer = _customer(client, headers)
+        owner = _personnel(client, headers)
+        part = _personnel(client, headers)
+        data = _create(client, headers, customer["id"], owner_personnel_id=owner["id"])
+
+        resp = client.put(
+            f"{_BUSINESSES}/{data['id']}",
+            json=_payload(
+                customer["id"],
+                secondary_allocations=[{"personnel_id": part["id"], "ratio": "40"}],
+            ),
+            headers=headers,
+        )
+        assert resp.status_code == 200, resp.text
+        # 方案在详情回包（更新回包为简版 Out，不含方案区）
+        detail = client.get(f"{_BUSINESSES}/{data['id']}", headers=headers).json()["data"]
+        assert len(detail["secondary_allocations"]) == 1
+        assert Decimal(detail["secondary_allocations"][0]["ratio"]) == Decimal("40")
+        # 余额 60% 归合同负责人（hint 文案 = #2 答复口径）
+        assert detail["allocation_hint"] is not None and "60" in detail["allocation_hint"]
+
 
 class TestStatus:
     """状态机：终态不可逆是终态单据禁写的前提；留痕从创建首条记起。"""