feat(allocation): 二次分配方案录入/替换/终态门槛（分摊计算待澄清另批）

- SecondaryAllocationIn/Out：比例走金额红线口径（str 入参、两位小数、
  超 100 拒绝不静默舍入）；参与人 schema 层去重（uk 前置友好提示）
- create/update 同事务写入（replace_allocations，先删后 flush 再插——
  uk 表防御写法）；create 放编号重试循环内，rollback 后方案随业务重来
- 人员在职复用 ensure_active（label=分摊参与），personnel_name 冗余固化；
  FK RESTRICT：被方案引用人员禁删，方案回显不静默失联
- 合计不强制 100%（需求原文）：详情 allocation_hint 只展示合计/余额，
  余额归属待澄清 #2 不落库
- 单测 13 例（比例边界/去重）+ 集成 9 例（回显/替换清空/离职 400/
  终态禁改/RESTRICT 保护）

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

backend/tests/unit/test_secondary_allocation_schema.py

@@ -0,0 +1,111 @@
+"""二次分配方案入参校验（schema 层，秒级）。
+
+守的是：比例红线（字符串入参、两位小数、超限拒绝不静默舍入）与
+参与人去重——uk(business_id, personnel_id) 的友好前置校验。
+明细行同批创建的正常路径由集成测试覆盖，这里集中打边界。
+"""
+
+import pytest
+from pydantic import ValidationError
+
+from app.schemas.business import SecondaryAllocationIn
+
+
+def _make(personnel_id: int = 1, ratio: str = "50.00") -> dict:
+    return {"personnel_id": personnel_id, "ratio": ratio}
+
+
+class TestRatioBoundary:
+    """比例边界：0 / 满额 / 超限 / 精度 / 非数字。"""
+
+    @pytest.mark.parametrize(
+        ("ratio", "ok"),
+        [
+            ("0", False),  # 必须大于 0
+            ("0.01", True),
+            ("33.33", True),
+            ("100", True),
+            ("100.00", True),
+            ("100.01", False),  # 超上限
+            ("-5", False),  # 负数
+            ("33.333", False),  # 三位小数：拒绝不静默舍入
+            ("abc", False),  # 非数字
+            ("", False),  # 空串
+        ],
+    )
+    def test_比例边界(self, ratio: str, *, ok: bool) -> None:
+        if ok:
+            assert SecondaryAllocationIn(**_make(ratio=ratio)).ratio == ratio
+        else:
+            with pytest.raises(ValidationError):
+                SecondaryAllocationIn(**_make(ratio=ratio))
+
+    def test_人员id必须为正整数(self) -> None:
+        with pytest.raises(ValidationError):
+            SecondaryAllocationIn(**_make(personnel_id=0))
+        with pytest.raises(ValidationError):
+            SecondaryAllocationIn(**_make(personnel_id=-1))
+
+
+class TestDuplicate:
+    """参与人去重（Create/Update 两个入参模型同款校验）。"""
+
+    def test_创建入参_重复参与人被拒(self) -> None:
+        from app.schemas.business import BusinessCreateIn
+
+        payload = {
+            "customer_id": 1,
+            "items": [
+                {
+                    "product_name": "t_产品",
+                    "product_category": "municipal_water",
+                    "quantity": "1.00",
+                    "sale_price": "10.00",
+                }
+            ],
+            "secondary_allocations": [
+                _make(personnel_id=5, ratio="30.00"),
+                _make(personnel_id=5, ratio="20.00"),
+            ],
+        }
+        with pytest.raises(ValidationError, match="重复"):
+            BusinessCreateIn(**payload)
+
+    def test_编辑入参_重复参与人被拒(self) -> None:
+        from app.schemas.business import BusinessUpdateIn
+
+        payload = {
+            "customer_id": 1,
+            "items": [
+                {
+                    "product_name": "t_产品",
+                    "product_category": "municipal_water",
+                    "quantity": "1.00",
+                    "sale_price": "10.00",
+                }
+            ],
+            "secondary_allocations": [_make(personnel_id=5), _make(personnel_id=5)],
+        }
+        with pytest.raises(ValidationError, match="重复"):
+            BusinessUpdateIn(**payload)
+
+    def test_不同参与人合法(self) -> None:
+        from app.schemas.business import BusinessCreateIn
+
+        payload = {
+            "customer_id": 1,
+            "items": [
+                {
+                    "product_name": "t_产品",
+                    "product_category": "municipal_water",
+                    "quantity": "1.00",
+                    "sale_price": "10.00",
+                }
+            ],
+            "secondary_allocations": [
+                _make(personnel_id=5, ratio="30.00"),
+                _make(personnel_id=6, ratio="20.00"),
+            ],
+        }
+        model = BusinessCreateIn(**payload)
+        assert len(model.secondary_allocations) == 2