feat: add way to tell if a converter reports progress

src/lib/converters/converter.svelte.ts

@@ -18,6 +18,7 @@ export class Converter {
 	 * @param to The format to convert to. Includes the dot.
 	 */
 	public ready: boolean = $state(false);
+	public readonly reportsProgress: boolean = false;
 
 	public async convert(
 		// eslint-disable-next-line @typescript-eslint/no-unused-vars

src/lib/converters/ffmpeg.svelte.ts

@@ -24,6 +24,8 @@ export class FFmpegConverter extends Converter {
 		".aiff",
 	];
 
+	public readonly reportsProgress = true;
+
 	constructor() {
 		super();
 		log(["converters", this.name], `created converter`);

src/lib/converters/vips.svelte.ts

@@ -29,6 +29,8 @@ export class VipsConverter extends Converter {
 		".tiff",
 	];
 
+	public readonly reportsProgress = false;
+
 	constructor() {
 		super();
 		log(["converters", this.name], `created converter`);