fix(annotations): add catch(err) binding to handlePointerUp error handler [M6]

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

frontend/src/lib/components/AnnotationEditOverlay.svelte

@@ -190,7 +190,8 @@ async function handlePointerUp(event: PointerEvent): Promise<void> {
 			width: liveWidth,
 			height: liveHeight
 		});
-	} catch {
+	} catch (err) {
+		console.error('annotation drag update failed', err);
 		liveX = ds.preDragX;
 		liveY = ds.preDragY;
 		liveWidth = ds.preDragWidth;