fix: harden financial transaction boundaries

apps/server/src/bills/dto/bill.dto.ts

@@ -1,6 +1,11 @@
 import { ArrayNotEmpty, IsArray, IsIn, IsInt, IsNotEmpty, IsOptional, IsString, Matches, MaxLength } from 'class-validator';
 
 export class GenerateBillsDto {
+  @IsOptional()
+  @IsString()
+  @Matches(/^[\w-]{8,64}$/)
+  operationId?: string;
+
   @IsString()
   @Matches(/^\d{4}-\d{2}$/)
   billingMonth: string;
@@ -20,6 +25,11 @@ export class UpdateBillStatusDto {
 }
 
 export class CancelBillDto {
+  @IsOptional()
+  @IsString()
+  @Matches(/^[\w-]{8,64}$/)
+  operationId?: string;
+
   @IsString()
   @IsNotEmpty()
   @Matches(/\S/)