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.server.ts

@@ -0,0 +1,67 @@
+import { createApiClient } from '$lib/api.server';
+import type { components, operations } from '$lib/generated/api';
+
+type ActivityFeedItemDTO = components['schemas']['ActivityFeedItemDTO'];
+type NotificationDTO = components['schemas']['NotificationDTO'];
+type AuditKind = NonNullable<operations['getActivity']['parameters']['query']>['kinds'] extends
+	| (infer K)[]
+	| undefined
+	? K
+	: never;
+
+export type FilterValue = 'alle' | 'fuer-dich' | 'hochgeladen' | 'transkription' | 'kommentare';
+
+const VALID_FILTERS: FilterValue[] = [
+	'alle',
+	'fuer-dich',
+	'hochgeladen',
+	'transkription',
+	'kommentare'
+];
+
+// fuer-dich stays client-side: youMentioned || youParticipated cannot be expressed as a kinds filter
+const KINDS_FOR_FILTER: Partial<Record<FilterValue, AuditKind[]>> = {
+	hochgeladen: ['FILE_UPLOADED'],
+	transkription: ['TEXT_SAVED', 'BLOCK_REVIEWED', 'ANNOTATION_CREATED'],
+	kommentare: ['COMMENT_ADDED', 'MENTION_CREATED']
+};
+
+function parseFilter(raw: string | null): FilterValue {
+	if (raw && (VALID_FILTERS as string[]).includes(raw)) return raw as FilterValue;
+	return 'alle';
+}
+
+export async function load({ fetch, url }) {
+	const api = createApiClient(fetch);
+	const filter = parseFilter(url.searchParams.get('filter'));
+	const limit = Math.min(Number(url.searchParams.get('limit')) || 40, 40);
+	const kinds = KINDS_FOR_FILTER[filter];
+
+	const [activityResult, unreadResult] = await Promise.allSettled([
+		api.GET('/api/dashboard/activity', { params: { query: { limit, ...(kinds && { kinds }) } } }),
+		api.GET('/api/notifications', {
+			params: { query: { read: false, page: 0, size: 20 } }
+		})
+	]);
+
+	let activityFeed: ActivityFeedItemDTO[] = [];
+	let unreadNotifications: NotificationDTO[] = [];
+	let loadError: string | null = null;
+
+	if (activityResult.status === 'fulfilled' && activityResult.value.response.ok) {
+		activityFeed = (activityResult.value.data as ActivityFeedItemDTO[]) ?? [];
+	} else if (activityResult.status === 'fulfilled') {
+		loadError = 'activity';
+	}
+
+	if (unreadResult.status === 'fulfilled' && unreadResult.value.response.ok) {
+		unreadNotifications = unreadResult.value.data?.content ?? [];
+	}
+
+	return {
+		filter,
+		activityFeed,
+		unreadNotifications,
+		loadError
+	};
+}