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/routes/aktivitaeten/+page.svelte

@@ -0,0 +1,127 @@
+<script lang="ts">
+import { onMount, onDestroy } from 'svelte';
+import { goto } from '$app/navigation';
+import { page, navigating } from '$app/state';
+import * as m from '$lib/paraglide/messages.js';
+import { notificationStore, type NotificationItem } from '$lib/stores/notifications.svelte';
+import ChronikFuerDichBox from '$lib/components/chronik/ChronikFuerDichBox.svelte';
+import ChronikFilterPills from '$lib/components/chronik/ChronikFilterPills.svelte';
+import ChronikTimeline from '$lib/components/chronik/ChronikTimeline.svelte';
+import ChronikEmptyState from '$lib/components/chronik/ChronikEmptyState.svelte';
+import ChronikErrorCard from '$lib/components/chronik/ChronikErrorCard.svelte';
+import type { components } from '$lib/generated/api';
+import type { FilterValue } from './+page.server';
+import { applyClientFilter } from './clientFilter';
+
+type ActivityFeedItemDTO = components['schemas']['ActivityFeedItemDTO'];
+
+interface Props {
+	data: {
+		filter: FilterValue;
+		activityFeed: ActivityFeedItemDTO[];
+		unreadNotifications: components['schemas']['NotificationDTO'][];
+		loadError: string | null;
+	};
+}
+
+const { data }: Props = $props();
+
+// Prefer the live SSE singleton for unread items so newly arriving mentions
+// prepend without a reload. On first mount, seed from the server-loaded unread
+// set if the singleton hasn't populated yet.
+onMount(() => {
+	notificationStore.init();
+});
+
+onDestroy(() => {
+	notificationStore.destroy();
+});
+
+const liveUnread = $derived<NotificationItem[]>(
+	notificationStore.notifications.filter((n) => !n.read)
+);
+
+const seedUnread = $derived<NotificationItem[]>(
+	data.unreadNotifications
+		.filter((n): n is typeof n & { documentId: string; referenceId: string } =>
+			Boolean(n.documentId && n.referenceId)
+		)
+		.map((n) => ({
+			id: n.id,
+			type: n.type,
+			documentId: n.documentId,
+			documentTitle: n.documentTitle ?? null,
+			referenceId: n.referenceId,
+			annotationId: n.annotationId ?? null,
+			read: n.read,
+			createdAt: n.createdAt,
+			actorName: n.actorName ?? ''
+		}))
+);
+
+// If the singleton has any data (including zero after mark-all), trust it;
+// otherwise fall back to the SSR-seeded unread set.
+const unread = $derived<NotificationItem[]>(
+	notificationStore.notifications.length > 0 ? liveUnread : seedUnread
+);
+
+async function onFilterChange(v: FilterValue) {
+	const url = new URL(page.url);
+	if (v === 'alle') url.searchParams.delete('filter');
+	else url.searchParams.set('filter', v);
+	await goto(`${url.pathname}${url.search}`, {
+		keepFocus: true,
+		noScroll: true,
+		replaceState: true
+	});
+}
+
+async function onMarkRead(n: NotificationItem) {
+	await notificationStore.markRead(n);
+}
+
+async function onMarkAllRead() {
+	await notificationStore.markAllRead();
+}
+
+const displayFeed = $derived(applyClientFilter(data.activityFeed, data.filter));
+
+const isEmpty = $derived(displayFeed.length === 0);
+const emptyVariant = $derived<'first-run' | 'filter-empty' | 'inbox-zero'>(
+	data.activityFeed.length === 0 ? 'first-run' : 'filter-empty'
+);
+
+function retry() {
+	location.reload();
+}
+</script>
+
+<svelte:head>
+	<title>{m.chronik_page_title()}</title>
+</svelte:head>
+
+<main class="mx-auto max-w-3xl px-4 py-8 sm:px-6 lg:px-8">
+	<header class="mb-6 flex items-baseline justify-between">
+		<h1 class="font-serif text-2xl text-ink">{m.chronik_page_title()}</h1>
+	</header>
+
+	{#if data.loadError === 'activity'}
+		<ChronikErrorCard onRetry={retry} />
+	{:else}
+		<ChronikFuerDichBox unread={unread} onMarkRead={onMarkRead} onMarkAllRead={onMarkAllRead} />
+
+		<div class="mt-6">
+			<ChronikFilterPills value={data.filter} onChange={onFilterChange} />
+		</div>
+
+		<div aria-live="polite" aria-atomic="false" aria-busy={!!navigating.type}>
+			{#if isEmpty}
+				<div class="mt-8">
+					<ChronikEmptyState variant={emptyVariant} />
+				</div>
+			{:else}
+				<ChronikTimeline items={displayFeed} />
+			{/if}
+		</div>
+	{/if}
+</main>