Add zk and hotlink upload create DTOs with batch options.

Split item shapes, array caps from config, and password-protected zk item transform.

backend/src/modules/upload/dto/CreateHotlinkUploadItemDto.ts

@@ -0,0 +1,9 @@
+import { IsMimeType, IsNotEmpty, IsString } from 'class-validator';
+import { CreateUploadCiphertextItemDto } from './CreateUploadCiphertextItemDto';
+
+export class CreateHotlinkUploadItemDto extends CreateUploadCiphertextItemDto {
+    @IsNotEmpty()
+    @IsString()
+    @IsMimeType()
+    mimeType: string;
+}