feat(chronik): rename route and heading to Aktivitäten

/chronik → /aktivitaeten; heading updated in all three locales.
Component folder (lib/components/chronik/) stays unchanged — internal
implementation detail, not user-facing.

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

frontend/src/lib/components/DashboardActivityFeed.svelte

@@ -56,7 +56,7 @@ function timestamp(item: ActivityFeedItemDTO): string {
 			{m.feed_caption()}
 		</h2>
 		<a
-			href="/chronik"
+			href="/aktivitaeten"
 			aria-label={m.feed_show_all()}
 			class="font-sans text-xs text-ink-3 transition-colors hover:text-ink">{m.feed_show_all()}</a
 		>