refactor(transcription): replace window.confirm with ConfirmService in TranscriptionBlock

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

frontend/src/lib/components/TranscriptionBlock.svelte

@@ -1,7 +1,10 @@
 <script lang="ts">
 import { m } from '$lib/paraglide/messages.js';
+import { getConfirmService } from '$lib/services/confirm.svelte.js';
 import CommentThread from './CommentThread.svelte';
 
+const { confirm } = getConfirmService();
+
 type SaveState = 'idle' | 'saving' | 'saved' | 'fading' | 'error';
 
 type Props = {
@@ -90,10 +93,12 @@ function handleInput(event: Event) {
 	onTextChange(target.value);
 }
 
-function handleDelete() {
-	if (confirm(m.transcription_block_delete_confirm())) {
-		onDeleteClick();
-	}
+async function handleDelete() {
+	const confirmed = await confirm({
+		title: m.transcription_block_delete_confirm(),
+		destructive: true
+	});
+	if (confirmed) onDeleteClick();
 }
 
 function handleTextareaMouseUp() {