enabled lazy loading for the Admin UI thumb images

ui/src/components/records/RecordFileThumb.svelte

@@ -65,6 +65,7 @@
                 src={thumbUrl}
                 alt={filename}
                 title="Preview {filename}"
+                loading="lazy"
                 on:error={onError}
             />
         {:else if type === "video" || type === "audio"}