test(e2e): add training footer positive-case test and fix broken selectors

- createEmptyDocument now uploads a minimal PDF so the Transkribieren
  button is rendered (requires isPdf = true in DocumentTopBar)
- add 'Transcribe coach — with blocks' describe: seeds a block via API,
  waits for blocks to settle in read mode, switches to edit, confirms
  'Für Training vormerken' is visible
- fix dark-theme axe test: ThemeToggle uses aria-label 'dark mode',
  not the previous /Farbmodus|theme/ regex

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

frontend/e2e/helpers/upload-empty-document.ts

@@ -1,10 +1,30 @@
 import type { APIRequestContext } from '@playwright/test';
+import path from 'path';
+import { fileURLToPath } from 'url';
+import fs from 'fs';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const PDF_FIXTURE = path.resolve(__dirname, '../fixtures/minimal.pdf');
 
 export async function createEmptyDocument(request: APIRequestContext): Promise<string> {
-	const res = await request.post('/api/documents', {
+	const createRes = await request.post('/api/documents', {
 		multipart: { title: 'E2E Transcribe Coach Test' }
 	});
-	if (!res.ok()) throw new Error(`Create document failed: ${res.status()}`);
-	const doc = await res.json();
-	return doc.id as string;
+	if (!createRes.ok()) throw new Error(`Create document failed: ${createRes.status()}`);
+	const doc = await createRes.json();
+	const docId = doc.id as string;
+
+	const uploadRes = await request.put(`/api/documents/${docId}`, {
+		multipart: {
+			title: doc.title,
+			file: {
+				name: 'minimal.pdf',
+				mimeType: 'application/pdf',
+				buffer: fs.readFileSync(PDF_FIXTURE)
+			}
+		}
+	});
+	if (!uploadRes.ok()) throw new Error(`Upload PDF failed: ${uploadRes.status()}`);
+
+	return docId;
 }

frontend/e2e/transcribe-coach.spec.ts

@@ -2,6 +2,24 @@ import { test, expect } from '@playwright/test';
 import AxeBuilder from '@axe-core/playwright';
 import { createEmptyDocument } from './helpers/upload-empty-document.js';
 
+async function createBlock(
+	request: Parameters<typeof createEmptyDocument>[0],
+	docId: string
+): Promise<void> {
+	const res = await request.post(`/api/documents/${docId}/transcription-blocks`, {
+		data: {
+			pageNumber: 1,
+			x: 0.1,
+			y: 0.1,
+			width: 0.3,
+			height: 0.1,
+			text: 'Liebe Mutter,',
+			label: null
+		}
+	});
+	if (!res.ok()) throw new Error(`Create block failed: ${res.status()}`);
+}
+
 function buildAxe(page: Parameters<typeof AxeBuilder>[0]['page']) {
 	return new AxeBuilder({ page }).withTags(['wcag2a', 'wcag2aa']);
 }
@@ -53,7 +71,7 @@ test.describe('Transcribe coach — empty state', () => {
 	test('axe: panel empty state — dark theme — no WCAG 2.1 AA violations', async ({ page }) => {
 		await page.goto(`/documents/${docId}`);
 		// Toggle dark theme
-		await page.getByRole('button', { name: /Farbmodus|theme/i }).click();
+		await page.getByRole('button', { name: /dark mode/i }).click();
 		await page.getByRole('button', { name: 'Transkribieren' }).click();
 		await expect(page.getByRole('heading', { level: 2, name: /Erste Transkription/ })).toBeVisible({
 			timeout: 5000
@@ -63,3 +81,25 @@ test.describe('Transcribe coach — empty state', () => {
 		expect(a11y.violations, JSON.stringify(a11y.violations, null, 2)).toHaveLength(0);
 	});
 });
+
+test.describe('Transcribe coach — with blocks', () => {
+	let docId: string;
+
+	test.beforeAll(async ({ request }) => {
+		docId = await createEmptyDocument(request);
+		await createBlock(request, docId);
+	});
+
+	test.afterAll(async ({ request }) => {
+		await request.delete(`/api/documents/${docId}`);
+	});
+
+	test('training footer IS visible when at least one block exists', async ({ page }) => {
+		await page.goto(`/documents/${docId}`);
+		await page.getByRole('button', { name: 'Transkribieren' }).click();
+		// Wait for blocks to finish loading — block count confirms mode settled to 'read'
+		await expect(page.getByText(/1 Abschnitt/)).toBeVisible({ timeout: 5000 });
+		await page.locator('[data-testid="mode-edit"]').click();
+		await expect(page.getByText('Für Training vormerken')).toBeVisible({ timeout: 5000 });
+	});
+});