feat(media): add image resizing support for processImage

Extend the `processImage` method to support optional resizing with `width` and `height` parameters. Update processing pipeline to handle resizing while maintaining existing format processing for `webp` and `avif`.

backend/src/media/media.service.ts

@@ -83,8 +83,9 @@ export class MediaService implements IMediaService {
 	async processImage(
 		buffer: Buffer,
 		format: "webp" | "avif" = "webp",
+		resize?: { width?: number; height?: number },
 	): Promise<MediaProcessingResult> {
-		return this.imageProcessor.process(buffer, { format });
+		return this.imageProcessor.process(buffer, { format, resize });
 	}
 
 	async processVideo(