R56 A1-A6：费用标准管控

server/prisma/schema.prisma

@@ -812,12 +812,36 @@ model ExpenseType {
   updated_at DateTime @default(now()) @updatedAt
   updated_by String?  @db.Uuid
 
+  standards           ExpenseStandard[]
   reimbursement_items ReimbursementItem[]
 
   @@index([enabled, sort_order])
   @@map("expense_types")
 }
 
+model ExpenseStandard {
+  id              String   @id @default(uuid()) @db.Uuid
+  expense_type_id String   @db.Uuid
+  name            String   @db.VarChar(100)
+  max_amount      Decimal  @db.Decimal(14, 2)
+  per_unit        String   @default("item") @db.VarChar(20)
+  control_mode    String   @default("warn") @db.VarChar(16)
+  scope_type      String   @default("global") @db.VarChar(32)
+  scope_key       String?  @db.Uuid
+  enabled         Boolean  @default(true)
+  note            String?
+
+  created_at DateTime @default(now())
+  created_by String?  @db.Uuid
+  updated_at DateTime @default(now()) @updatedAt
+  updated_by String?  @db.Uuid
+
+  expense_type ExpenseType @relation(fields: [expense_type_id], references: [id], onDelete: Restrict)
+
+  @@index([enabled, expense_type_id], map: "idx_expense_standards_enabled_type")
+  @@map("expense_standards")
+}
+
 model DocumentSequence {
   document_type   String              @id
   prefix          String