refactor: centralize domain values and enforce numeric lint

src/modules/investments/tbank-connection/tbank-connection.dto.ts

@@ -1,11 +1,13 @@
 import { ApiProperty } from '@nestjs/swagger';
 import { IsNotEmpty, IsString, MaxLength } from 'class-validator';
 
+const MAX_TOKEN_LENGTH = 4096;
+
 export class PutTbankConnectionDto {
   @ApiProperty({ writeOnly: true })
   @IsString()
   @IsNotEmpty()
-  @MaxLength(4096)
+  @MaxLength(MAX_TOKEN_LENGTH)
   declare token: string;
 }