refactor: retire legacy tbank-sync status and sync=observe (WealthLedger/backend#196)

src/modules/investments/investment-resource.dto.ts

@@ -1,5 +1,4 @@
 import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
-import { IsIn, IsOptional } from 'class-validator';
 
 export const availabilityValues = [
   'available',
@@ -17,13 +16,6 @@ export const attemptStateValues = [
   'failed',
 ] as const;
 
-export class InvestmentReadQueryDto {
-  @ApiPropertyOptional({ enum: ['observe'] })
-  @IsOptional()
-  @IsIn(['observe'])
-  declare sync?: 'observe';
-}
-
 export class InvestmentAttemptProblemDto {
   @ApiProperty({ enum: ['membership', 'portfolio', 'operations', 'events'] })
   declare section: 'events' | 'membership' | 'operations' | 'portfolio';