fix(tests): resolve all 4 pre-existing test failures

- CommentThread: add missing empty-state paragraph using comment_empty_hint
  i18n key (key existed but was never rendered in the template)
- TranscriptionBlock: add selectedQuote hint using transcription_block_quote_hint
  i18n key (key existed but was never rendered); fix test to use native DOM
  el.focus()/setSelectionRange()/dispatchEvent instead of locator.selectText()
  which is not available in this vitest-browser version
- TranscriptionEditView: fix test to use native el.dispatchEvent(FocusEvent)
  instead of locator.blur() which is not available
- Conversations: fix test expected text from stale "Korrespondenz durchsuchen"
  to match current conv_empty_heading() = "Wessen Briefe möchten Sie lesen?"

All 687 tests now pass.

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

frontend/src/lib/components/CommentThread.svelte

@@ -199,7 +199,9 @@ onMount(() => {
 });
 </script>
 
-{#if flatMessages.length > 0}
+{#if flatMessages.length === 0}
+	<p class="text-sm text-ink-3 italic">{m.comment_empty_hint()}</p>
+{:else}
 	<div class="rounded border-l-2 border-accent bg-muted p-2">
 		<div class="mb-2 flex items-center gap-1.5 font-sans text-sm font-semibold text-ink-2">
 			<svg

frontend/src/lib/components/TranscriptionBlock.svelte

@@ -182,6 +182,10 @@ function handleTextareaMouseUp() {
 			onmouseup={handleTextareaMouseUp}
 		></textarea>
 
+		{#if selectedQuote}
+			<p class="mt-1 text-xs text-ink-3">{m.transcription_block_quote_hint()}</p>
+		{/if}
+
 		<!-- Footer -->
 		<div class="flex items-center justify-between border-t border-line pt-2">
 			<div>

frontend/src/lib/components/TranscriptionBlock.svelte.spec.ts

@@ -228,12 +228,12 @@ describe('TranscriptionBlock — delete confirmation', () => {
 describe('TranscriptionBlock — quote selection', () => {
 	it('shows quote hint after text is selected in textarea', async () => {
 		renderBlock({ text: 'Breslau, den 12. August' });
-		const textarea = page.getByRole('textbox');
-		// Select all text via keyboard shortcut to trigger mouseup with selection
-		await textarea.click();
-		await textarea.selectText();
-		// Fire mouseup to trigger the selection handler
-		await textarea.dispatchEvent('mouseup');
+		await page.getByRole('textbox').click();
+		// Select text and fire mouseup via native DOM — locator.selectText/dispatchEvent not available
+		const el = document.querySelector('textarea') as HTMLTextAreaElement;
+		el.focus();
+		el.setSelectionRange(0, el.value.length);
+		el.dispatchEvent(new MouseEvent('mouseup', { bubbles: true }));
 		await expect.element(page.getByText(/Zitat/)).toBeInTheDocument();
 	});
 });

frontend/src/lib/components/TranscriptionEditView.svelte.spec.ts

@@ -193,8 +193,9 @@ describe('TranscriptionEditView — flush on blur', () => {
 		const textarea = page.getByRole('textbox').first();
 		await textarea.fill('Blur text');
 
-		// Blur before 1500ms debounce fires
-		await textarea.blur();
+		// Blur before 1500ms debounce fires — locator.blur() not available, use native DOM
+		const el = document.querySelector('textarea') as HTMLTextAreaElement;
+		el.dispatchEvent(new FocusEvent('blur', { bubbles: true }));
 
 		await vi.runAllTimersAsync();
 		expect(onSaveBlock).toHaveBeenCalledWith('b1', 'Blur text');

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

@@ -50,7 +50,7 @@ const withDocs = {
 describe('Conversations page – empty state', () => {
 	it('shows the empty-state heading when no persons are selected', async () => {
 		render(Page, { data: baseData });
-		await expect.element(page.getByText(/Korrespondenz durchsuchen/i)).toBeInTheDocument();
+		await expect.element(page.getByText(/Wessen Briefe möchten Sie lesen/i)).toBeInTheDocument();
 	});
 
 	it('hides the swap button when no persons are selected', async () => {