fix(bulk-upload): raise discard button touch target to 44px for WCAG compliance

Senior users on tablets need at least 44×44px touch targets (WCAG 2.2).
Added min-h-[44px] flex items-center px-2 to the discard button.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/components/document/UploadSaveBar.svelte

@@ -27,7 +27,11 @@ let {
 		></progress>
 	{/if}
 	<div class="flex items-center justify-between gap-3">
-		<button type="button" onclick={onDiscard} class="text-sm text-red-600/70 hover:text-red-700">
+		<button
+			type="button"
+			onclick={onDiscard}
+			class="flex min-h-[44px] items-center px-2 text-sm text-red-600/70 hover:text-red-700"
+		>
 			{m.bulk_discard_all()}
 		</button>
 		<button