feat: 20260805 系统优化 - 身份证复制fallback/薪税日期筛选/社保版本修复/证据链导出/违纪证明/医疗期政策/绩效类型评级/合同作废/帮助更新

backend/prisma/schema.prisma

@@ -195,6 +195,7 @@ model Organization {
   benefitPlans         EmployeeBenefitPlan[]
   benefitEnrollments   EmployeeBenefitEnrollment[]
   eSignRecords         ESignRecord[]
+  medicalPeriodPolicies MedicalPeriodPolicy[]
 }
 
 model User {
@@ -500,6 +501,21 @@ model OvertimeConfig {
   updatedAt       DateTime @updatedAt
 }
 
+model MedicalPeriodPolicy {
+  id          String   @id @default(cuid())
+  orgId       String
+  org         Organization @relation(fields: [orgId], references: [id], onDelete: Cascade)
+  region      String   // 地区名称，如"全国"、"上海"、"广东"
+  legalBasis  String   // 法律依据
+  rules       Json     // 分档规则: [{ maxYears: 5, months: 3, cycleMonths: 6 }, ...]
+  isDefault   Boolean  @default(false)
+  createdAt   DateTime @default(now())
+  updatedAt   DateTime @updatedAt
+
+  @@unique([orgId, region])
+  @@index([orgId])
+}
+
 model NotificationLog {
   id          String   @id @default(cuid())
   orgId       String