feat(api): add per-type file size limits and 413 responses for media uploads

- FileValidationPipe now supports maxSizeByMimeType for per-MIME-type size limits
- Images: max 10MB, Video (MP4): max 100MB
- Oversized files return 413 Payload Too Large instead of 400 Bad Request
- MIME type validation runs before size check for clearer error messages
- Multer module limit raised to 100MB (per-type enforcement in pipe)
- Added 413 ApiResponse to Swagger docs on upload endpoint
- Added comprehensive unit tests for FileValidationPipe (16 test cases)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/listings/presentation/controllers/listings.controller.ts

@@ -169,13 +169,17 @@ export class ListingsController {
   @ApiParam({ name: 'id', description: 'Listing UUID' })
   @ApiResponse({ status: 201, description: 'Media uploaded successfully' })
   @ApiResponse({ status: 401, description: 'Unauthorized' })
+  @ApiResponse({ status: 413, description: 'File too large (images: max 10MB, video: max 100MB)' })
   @UseGuards(JwtAuthGuard)
   @UseInterceptors(FileInterceptor('file'))
   @Post(':id/media')
   async uploadMedia(
     @Param('id') id: string,
     @UploadedFile(new FileValidationPipe({
-      maxSizeBytes: 10 * 1024 * 1024, // 10 MB
+      maxSizeBytes: 10 * 1024 * 1024, // 10 MB default for images
+      maxSizeByMimeType: {
+        'video/mp4': 100 * 1024 * 1024, // 100 MB for video
+      },
       allowedMimeTypes: ['image/jpeg', 'image/png', 'image/webp', 'video/mp4'],
     }))
     file: ValidatedFile,