perf: reuse preview on apply instead of reprocessing

Pass the already-processed preview data URL when applying edits.
The thumbnail updates instantly without triggering another process cycle.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/lib/components/EditImageModal.svelte

@@ -11,7 +11,7 @@
 		image: ImageEntry | null;
 		device: Device;
 		onClose: () => void;
-		onApply: (imageId: string, config: PipelineConfig) => void;
+		onApply: (imageId: string, config: PipelineConfig, processedDataUrl: string | null) => void;
 	}
 
 	let { open, image, device, onClose, onApply }: Props = $props();
@@ -36,7 +36,7 @@
 
 	function handleApply(): void {
 		if (!image) return;
-		onApply(image.id, localConfig);
+		onApply(image.id, localConfig, previewDataUrl);
 		onClose();
 	}
 

src/routes/+page.svelte

@@ -89,9 +89,15 @@
 		editingImage = null;
 	}
 
-	function handleApplyPipeline(imageId: string, config: PipelineConfig): void {
+	function handleApplyPipeline(imageId: string, config: PipelineConfig, processedDataUrl: string | null): void {
 		imagesStore.setPipelineOverride(imageId, config);
-		imagesStore.reprocessImage(imageId, deviceStore.selected);
+		if (processedDataUrl) {
+			// Use the already-processed preview directly
+			imagesStore.updateImage(imageId, { processedDataUrl });
+		} else {
+			// Fallback: reprocess if no preview available
+			imagesStore.reprocessImage(imageId, deviceStore.selected);
+		}
 	}
 
 	function handleClearAll(): void {