fix(F-06): auto-open crop editor after image upload on item detail

Added onCropChange and dominantColor props to ImageUpload in the item
detail page, so the crop editor opens automatically after uploading
a new image.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/client/routes/items/$itemId.tsx

@@ -273,9 +273,18 @@ function ItemDetail() {
 					<ImageUpload
 						value={form.imageFilename}
 						imageUrl={imageUrl}
+						dominantColor={item.dominantColor}
 						onChange={(filename) =>
 							setForm((f) => ({ ...f, imageFilename: filename }))
 						}
+						onCropChange={(crop) => {
+							updateItem.mutate({
+								id: item.id,
+								cropZoom: crop.zoom,
+								cropX: crop.x,
+								cropY: crop.y,
+							});
+						}}
 					/>
 				</div>
 			) : editingCrop && imageUrl ? (