fix(transcription): reload annotations after drawing block on PDF

After onTranscriptionDraw callback completes, reload the annotation
list from the backend so the turquoise rectangle overlay appears
immediately on the PDF page.

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

frontend/src/lib/components/PdfViewer.svelte

@@ -208,7 +208,8 @@ async function handleDraw(rect: { x: number; y: number; width: number; height: n
 	if (!documentId) return;
 
 	if (transcribeMode) {
-		onTranscriptionDraw?.({ ...rect, pageNumber: currentPage });
+		await onTranscriptionDraw?.({ ...rect, pageNumber: currentPage });
+		await loadAnnotations(documentId);
 		return;
 	}