refactor(chronik): replace callback props with form actions in ChronikFuerDichBox

Dismiss (X) button and mark-all-read button now submit forms to
/aktivitaeten?/dismiss-notification and /aktivitaeten?/mark-all-read respectively.
Props renamed onMarkRead/onMarkAllRead → optimisticMarkRead/optimisticMarkAllRead.

aktivitaeten/+page.svelte drops the now-deleted onMarkRead/onMarkAllRead wrapper functions
and passes notificationStore.optimisticMarkRead/optimisticMarkAllRead directly to the box.

Tests: $app/forms enhance mock added to both spec files so dismiss and mark-all assertions
work synchronously against form-submit events.

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

frontend/src/lib/activity/ChronikFuerDichBox.svelte.test.ts

@@ -4,6 +4,17 @@ import { page } from 'vitest/browser';
 import ChronikFuerDichBox from './ChronikFuerDichBox.svelte';
 import type { NotificationItem } from '$lib/notification/notifications';
 
+vi.mock('$app/forms', () => ({
+	enhance(node: HTMLFormElement, submit?: (opts: { formData: FormData }) => unknown) {
+		const handler = (e: Event) => {
+			e.preventDefault();
+			submit?.({ formData: new FormData(node) } as never);
+		};
+		node.addEventListener('submit', handler);
+		return { destroy: () => node.removeEventListener('submit', handler) };
+	}
+}));
+
 afterEach(cleanup);
 
 const mention = (overrides: Partial<NotificationItem> = {}): NotificationItem => ({
@@ -22,7 +33,7 @@ const mention = (overrides: Partial<NotificationItem> = {}): NotificationItem =>
 describe('ChronikFuerDichBox', () => {
 	it('renders the inbox-zero state when there are no unread', async () => {
 		render(ChronikFuerDichBox, {
-			props: { unread: [], onMarkRead: () => {}, onMarkAllRead: () => {} }
+			props: { unread: [], optimisticMarkRead: () => {}, optimisticMarkAllRead: () => {} }
 		});
 
 		await expect.element(page.getByText(/keine neuen erwähnungen/i)).toBeVisible();
@@ -34,8 +45,8 @@ describe('ChronikFuerDichBox', () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention(), mention({ id: 'n-2' }), mention({ id: 'n-3' })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
@@ -47,8 +58,8 @@ describe('ChronikFuerDichBox', () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention({ id: 'n-m', type: 'MENTION' }), mention({ id: 'n-r', type: 'REPLY' })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
@@ -62,8 +73,8 @@ describe('ChronikFuerDichBox', () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention({ actorName: 'Bertha' })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
@@ -76,8 +87,8 @@ describe('ChronikFuerDichBox', () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention({ type: 'REPLY', actorName: 'Carl' })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
@@ -86,11 +97,11 @@ describe('ChronikFuerDichBox', () => {
 			.toBeVisible();
 	});
 
-	it('calls onMarkRead with the notification when its dismiss button is clicked', async () => {
-		const onMarkRead = vi.fn();
+	it('calls optimisticMarkRead with the notification id when its dismiss button is clicked', async () => {
+		const optimisticMarkRead = vi.fn();
 		const item = mention({ id: 'n-7' });
 		render(ChronikFuerDichBox, {
-			props: { unread: [item], onMarkRead, onMarkAllRead: () => {} }
+			props: { unread: [item], optimisticMarkRead, optimisticMarkAllRead: () => {} }
 		});
 
 		const dismiss = document.querySelector(
@@ -98,31 +109,31 @@ describe('ChronikFuerDichBox', () => {
 		) as HTMLElement;
 		dismiss.click();
 
-		expect(onMarkRead).toHaveBeenCalledWith(item);
+		expect(optimisticMarkRead).toHaveBeenCalledWith('n-7');
 	});
 
-	it('calls onMarkAllRead when the mark-all-read button is clicked', async () => {
-		const onMarkAllRead = vi.fn();
+	it('calls optimisticMarkAllRead when the mark-all-read button is clicked', async () => {
+		const optimisticMarkAllRead = vi.fn();
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention()],
-				onMarkRead: () => {},
-				onMarkAllRead
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead
 			}
 		});
 
 		const btn = document.querySelector('[data-testid="chronik-mark-all-read"]') as HTMLElement;
 		btn.click();
 
-		expect(onMarkAllRead).toHaveBeenCalledOnce();
+		expect(optimisticMarkAllRead).toHaveBeenCalledOnce();
 	});
 
 	it('builds a deep-link href to the comment for each notification', async () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention({ documentId: 'doc-x', referenceId: 'ref-y', annotationId: null })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});