fix(comments): show either created or edited timestamp, not both

Unedited comments show "vor X Minuten". Edited comments show
"vor X Minuten (Bearbeitet)" using the updatedAt timestamp.
Reduces visual noise in comment threads.

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

frontend/src/lib/components/CommentThread.svelte

@@ -259,12 +259,12 @@ onMount(async () => {
 			<div class="min-w-0 flex-1">
 				<div class="flex flex-wrap items-center gap-2">
 					<span class="font-sans text-xs font-semibold text-ink">{comment.authorName}</span>
-					<span class="font-sans text-xs text-ink-3">{timeAgo(comment.createdAt)}</span>
 					{#if wasEdited(comment)}
-						<span class="font-sans text-xs text-ink-3">
-							{m.comment_edited_label()}
-							{timeAgo(comment.updatedAt)}
-						</span>
+						<span class="font-sans text-xs text-ink-3"
+							>{timeAgo(comment.updatedAt)} (Bearbeitet)</span
+						>
+					{:else}
+						<span class="font-sans text-xs text-ink-3">{timeAgo(comment.createdAt)}</span>
 					{/if}
 				</div>
 				<p class="mt-1 font-serif text-sm leading-relaxed text-ink-2">