test: cover geschichten/new and geschichten/[id]/edit page renders

Both pages embed GeschichteEditor (TipTap-based). The tests assert
heading, BackButton presence, no-error default, editor inputs render,
and prop pass-through (initialPersons / initialDocuments). $app/navigation
is mocked because GeschichteEditor pulls beforeNavigate transitively.

Refs #496.

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

frontend/src/routes/geschichten/new/page.svelte.test.ts

@@ -0,0 +1,70 @@
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+
+vi.mock('$app/navigation', () => ({
+	beforeNavigate: () => {},
+	afterNavigate: () => {},
+	goto: vi.fn(),
+	invalidate: vi.fn(),
+	invalidateAll: vi.fn(),
+	preloadCode: vi.fn(),
+	preloadData: vi.fn(),
+	pushState: vi.fn(),
+	replaceState: vi.fn(),
+	disableScrollHandling: vi.fn(),
+	onNavigate: () => () => {}
+}));
+
+const { default: GeschichtenNewPage } = await import('./+page.svelte');
+
+afterEach(cleanup);
+
+const baseData = {
+	initialPersons: [] as { id: string; displayName: string }[],
+	initialDocuments: [] as { id: string; title: string }[]
+};
+
+describe('geschichten/new page', () => {
+	it('renders the page heading', async () => {
+		render(GeschichtenNewPage, { props: { data: baseData } });
+
+		await expect.element(page.getByRole('heading', { level: 1 })).toBeVisible();
+	});
+
+	it('renders a button (BackButton component)', async () => {
+		render(GeschichtenNewPage, { props: { data: baseData } });
+
+		const buttons = document.querySelectorAll('button');
+		expect(buttons.length).toBeGreaterThan(0);
+	});
+
+	it('does not render an error banner by default', async () => {
+		render(GeschichtenNewPage, { props: { data: baseData } });
+
+		expect(document.querySelector('[role="alert"]')).toBeNull();
+	});
+
+	it('renders the GeschichteEditor child component', async () => {
+		render(GeschichtenNewPage, { props: { data: baseData } });
+
+		// Editor renders inputs/textarea — verify at least one form input is present
+		const inputs = document.querySelectorAll('input, textarea');
+		expect(inputs.length).toBeGreaterThan(0);
+	});
+
+	it('passes initialPersons and initialDocuments through to the editor', async () => {
+		render(GeschichtenNewPage, {
+			props: {
+				data: {
+					initialPersons: [{ id: 'p1', displayName: 'Anna Schmidt' }],
+					initialDocuments: [{ id: 'd1', title: 'Brief 1923' }]
+				}
+			}
+		});
+
+		// Both should appear somewhere in the rendered editor
+		await expect.element(page.getByText('Anna Schmidt')).toBeVisible();
+		await expect.element(page.getByText('Brief 1923')).toBeVisible();
+	});
+});