feat(isac): support deferred item icons

src/lib/components/ImageUploadInput.svelte

@@ -6,6 +6,7 @@
 		accept,
 		required = false,
 		currentUrl = '',
+		placeholderUrl = '',
 		emptyLabel = 'NO IMAGE',
 		browseLabel = 'CHOOSE FILE',
 		resetToken = 0
@@ -14,6 +15,7 @@
 		accept: string;
 		required?: boolean;
 		currentUrl?: string | null;
+		placeholderUrl?: string | null;
 		emptyLabel?: string;
 		browseLabel?: string;
 		resetToken?: string | number;
@@ -120,8 +122,8 @@
 >
 	<input bind:this={input} class="image-file-input" {name} type="file" {accept} {required} onchange={choose}/>
 	<div class="image-upload-preview">
-		{#if previewUrl || currentUrl}
-			<img src={previewUrl || currentUrl || ''} alt="Selected upload preview"/>
+		{#if previewUrl || currentUrl || placeholderUrl}
+			<img class:missing-item-icon={!previewUrl && !currentUrl && Boolean(placeholderUrl)} src={previewUrl || currentUrl || placeholderUrl || ''} alt={previewUrl || currentUrl ? 'Selected upload preview' : emptyLabel}/>
 		{:else}
 			<span>{emptyLabel}</span>
 		{/if}