fix(tests): fix 27 failing frontend unit tests

Six categories of breakage:

1. date.ts — add formatGermanDateInput(raw: string): string as a pure
   function covering both digit-stream auto-dot and manual-dot-with-padding
   modes. Refactor handleGermanDateInput to delegate to it. Fixes 16 failures
   in date.spec.ts where the function was imported but didn't exist.

2. Admin layout specs (groups/tags/users) — $effect fires on initial mount
   with manualCollapse=false, so the spy captured 'false' before the click's
   effect ran. Fix: move spy setup after render(), add await setTimeout(0) to
   flush Svelte effects before asserting.

3. DashboardMentions — component now renders a persistent
   "Benachrichtigungsverlauf ansehen" link, making getByRole('link') strict-
   mode violations. Fix: scope link queries to the actor name, and check
   absence of the actor link (not all links) in the no-documentId test.

4. Conversations page — empty-state copy changed from "Wählen Sie zwei
   Personen aus" to "Korrespondenz durchsuchen". Update the test.

5. Login page — AuthHeader adds a second aria-label="Familienarchiv" link.
   Use .first() to avoid strict-mode violation.

6. Persons page — alias is rendered with German quotation marks „…" not
   straight quotes "…". Update the test string.

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

frontend/src/routes/admin/groups/layout.svelte.spec.ts

@@ -109,9 +109,10 @@ describe('GroupsListPanel — collapse toggle', () => {
 	});
 
 	it('persists collapse state using the groups-specific localStorage key', async () => {
-		const setSpy = vi.spyOn(Storage.prototype, 'setItem');
 		render(GroupsListPanel, { groups });
+		const setSpy = vi.spyOn(Storage.prototype, 'setItem');
 		document.querySelector<HTMLButtonElement>('[aria-label="Liste einklappen"]')!.click();
+		await new Promise((r) => setTimeout(r, 0));
 		expect(setSpy).toHaveBeenCalledWith('admin_groups_list_collapsed', 'true');
 		setSpy.mockRestore();
 	});

frontend/src/routes/admin/tags/layout.svelte.spec.ts

@@ -88,9 +88,10 @@ describe('TagsListPanel — collapse toggle', () => {
 	});
 
 	it('persists collapse state using the tags-specific localStorage key', async () => {
-		const setSpy = vi.spyOn(Storage.prototype, 'setItem');
 		render(TagsListPanel, { tags });
+		const setSpy = vi.spyOn(Storage.prototype, 'setItem');
 		document.querySelector<HTMLButtonElement>('[aria-label="Liste einklappen"]')!.click();
+		await new Promise((r) => setTimeout(r, 0));
 		expect(setSpy).toHaveBeenCalledWith('admin_tags_list_collapsed', 'true');
 		setSpy.mockRestore();
 	});

frontend/src/routes/admin/users/layout.svelte.spec.ts

@@ -131,9 +131,10 @@ describe('UsersListPanel — collapse toggle', () => {
 	});
 
 	it('persists collapse state using the users-specific localStorage key', async () => {
-		const setSpy = vi.spyOn(Storage.prototype, 'setItem');
 		render(UsersListPanel, { users });
+		const setSpy = vi.spyOn(Storage.prototype, 'setItem');
 		document.querySelector<HTMLButtonElement>('[aria-label="Liste einklappen"]')!.click();
+		await new Promise((r) => setTimeout(r, 0));
 		expect(setSpy).toHaveBeenCalledWith('admin_users_list_collapsed', 'true');
 		setSpy.mockRestore();
 	});

frontend/src/routes/conversations/page.svelte.spec.ts

@@ -48,9 +48,9 @@ const withDocs = {
 // ─── Empty state ──────────────────────────────────────────────────────────────
 
 describe('Conversations page – empty state', () => {
-	it('shows the "select two persons" prompt when no persons are selected', async () => {
+	it('shows the empty-state heading when no persons are selected', async () => {
 		render(Page, { data: baseData });
-		await expect.element(page.getByText(/Wählen Sie zwei Personen aus/i)).toBeInTheDocument();
+		await expect.element(page.getByText(/Korrespondenz durchsuchen/i)).toBeInTheDocument();
 	});
 
 	it('hides the swap button when no persons are selected', async () => {

frontend/src/routes/login/page.svelte.spec.ts

@@ -10,7 +10,9 @@ afterEach(cleanup);
 describe('Login page – rendering', () => {
 	it('renders the page title', async () => {
 		render(LoginPage, {});
-		await expect.element(page.getByRole('link', { name: 'Familienarchiv' })).toBeInTheDocument();
+		await expect
+			.element(page.getByRole('link', { name: 'Familienarchiv' }).first())
+			.toBeInTheDocument();
 		await page.screenshot({ path: 'test-results/screenshots/login-default.png' });
 	});
 

frontend/src/routes/persons/page.svelte.spec.ts

@@ -64,7 +64,7 @@ describe('Persons page – rendering', () => {
 
 	it('shows alias in italic when provided', async () => {
 		render(Page, { data: { ...emptyData, persons: [makePerson({ alias: 'Maxi' })] } });
-		await expect.element(page.getByText('"Maxi"')).toBeInTheDocument();
+		await expect.element(page.getByText('„Maxi"')).toBeInTheDocument();
 	});
 
 	it('shows life date range when birthYear is provided', async () => {