test(admin/system): cover the system page render branches

Backfill cards rendered, both backfill buttons enabled by default,
no success banner before any action. Smoke-level coverage of the
admin maintenance page.

5 tests covering basic render branches.

Refs #496.

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

frontend/src/routes/admin/system/page.svelte.test.ts

@@ -0,0 +1,49 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import AdminSystemPage from './+page.svelte';
+
+afterEach(cleanup);
+
+describe('admin/system page', () => {
+	it('renders the backfill versions card', async () => {
+		render(AdminSystemPage, { props: {} });
+
+		await expect
+			.element(page.getByRole('heading', { name: /verlaufsdaten auffüllen/i }))
+			.toBeVisible();
+	});
+
+	it('renders the backfill versions button enabled by default', async () => {
+		render(AdminSystemPage, { props: {} });
+
+		const btn = (await page
+			.getByRole('button', { name: /jetzt auffüllen/i })
+			.element()) as HTMLButtonElement;
+		expect(btn.disabled).toBe(false);
+	});
+
+	it('renders the backfill file-hashes card', async () => {
+		render(AdminSystemPage, { props: {} });
+
+		await expect
+			.element(page.getByRole('heading', { name: /datei-hashes berechnen/i }))
+			.toBeVisible();
+	});
+
+	it('renders the backfill file-hashes button enabled by default', async () => {
+		render(AdminSystemPage, { props: {} });
+
+		const btn = (await page
+			.getByRole('button', { name: /datei-hashes berechnen/i })
+			.element()) as HTMLButtonElement;
+		expect(btn.disabled).toBe(false);
+	});
+
+	it('does not render the backfill success banner before any action', async () => {
+		render(AdminSystemPage, { props: {} });
+
+		const banners = document.querySelectorAll('.bg-green-50');
+		expect(banners.length).toBe(0);
+	});
+});