feat(settlement): 月度结算快照生成与审批锁定，调整单（补发/扣减）与审批联动

- settlement_service：generate（确认回款口径 #8 策略点=有效台账行按回款日
  归月、经理聚合 #12 暂口径基数不含经理个人户、月结 uk 一行一月、草稿/
  驳回可重生成、已审定/待审 400）→ submit（审批开关分流，关=自动通过即
  锁定、开=待财务复核）→ approval_service.act 扩 order_type=2/3 钩子
  （通过=mark_locked/调整单生效；驳回=回草稿/作废，延迟导入防循环）
- 锁定拦截：回款新增写路径校验回款月已审定 400（比需求「提示」取硬，
  一期安全侧；M2 已核算禁改防线先于其生效）
- 调整单：新建（TZ 单号，开关分流自动通过留痕/走审批）+ 列表
- schemas settlement：金额 Decimal 声明（str 声明遇 Decimal 入参拒绝）
- 测试 6 例：生成回填/无记录 400/已审定重生成 400/关自动锁定/锁定后回款
  禁改/开两节点流转至锁定（finance→leader）

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

backend/app/schemas/settlement.py

@@ -0,0 +1,90 @@
+"""月度结算的请求/响应模型（M3 ④）。"""
+
+import re
+from datetime import datetime
+from decimal import Decimal
+
+from pydantic import BaseModel, ConfigDict, Field, field_validator
+
+from app.core.response import PageQuery
+
+_MONTH_RE = re.compile(r"^\d{4}-\d{2}$")
+
+
+def _check_month(value: str) -> str:
+    """月份格式 YYYY-MM（settlement_month 全表唯一的维度）。"""
+    if not _MONTH_RE.match(value):
+        raise ValueError("月份格式须为 YYYY-MM")
+    return value
+
+
+class SettlementGenerateIn(BaseModel):
+    """月结生成入参。"""
+
+    month: str = Field(description="结算月份 YYYY-MM")
+
+    @field_validator("month")
+    @classmethod
+    def _v_month(cls, value: str) -> str:
+        return _check_month(value)
+
+
+class SettlementQuery(PageQuery):
+    """月结列表查询。"""
+
+    status: int | None = Field(default=None, ge=1, le=4, description="状态筛选")
+
+
+class SettlementItemOut(BaseModel):
+    """月结明细行。"""
+
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    personnel_id: int
+    personnel_name: str
+    role_code: str
+    calc_type: int
+    performance_sum: Decimal
+    payable_sum: Decimal
+    basic_amount: Decimal | None = None
+    salary_mode: str | None = None
+    net_amount: Decimal | None = None
+    is_probation: int
+    probation_note: str | None = None
+
+
+class SettlementOut(BaseModel):
+    """月结头表响应。"""
+
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    settlement_month: str
+    status: int
+    total_performance: Decimal | None = None
+    total_payable: Decimal | None = None
+    person_count: int
+    approval_order_no: str | None = None
+    submitter_name: str
+    locked_at: datetime | datetime | None = None
+    locked_by: str | None = None
+    create_time: datetime
+
+
+class SettlementDetailOut(SettlementOut):
+    """月结详情：附明细。"""
+
+    items: list[SettlementItemOut] = Field(default_factory=list)
+
+
+class AdjustmentCreateIn(BaseModel):
+    """调整单创建入参（金额恒正，方向表达补发/扣减）。"""
+
+    model_config = ConfigDict(str_strip_whitespace=True)
+
+    settlement_month: str = Field(description="调整月份 YYYY-MM")
+    personnel_id: int = Field(ge=1, description="调整人员ID")
+    direction: int = Field(ge=1, le=2, description="1补发 2扣减")
+    amount: str = Field(description="金额（元，两位小数）")
+    reason: str = Field(min_length=1, max_length=255, description="扣补说明")