fix: bump comment text to text-base + reload annotations on block delete

Comment text:
- Body and quote bumped from text-sm (14px) to text-base (16px)
  to visually match the font-sans author name at text-sm

Annotation reload on delete:
- Add annotationReloadKey prop through DocumentViewer → PdfViewer
- Increment key after block delete in +page.svelte
- PdfViewer reloads annotations when key changes
- Annotation rectangle disappears immediately, not just after refresh

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

frontend/src/lib/components/DocumentViewer.svelte

@@ -18,6 +18,7 @@ type Props = {
 	error: string;
 	transcribeMode?: boolean;
 	blockNumbers?: Record<string, number>;
+	annotationReloadKey?: number;
 	activeAnnotationId: string | null;
 	onAnnotationClick: (id: string) => void;
 	onTranscriptionDraw?: (rect: DrawRect) => void;
@@ -30,6 +31,7 @@ let {
 	error,
 	transcribeMode = false,
 	blockNumbers = {},
+	annotationReloadKey = 0,
 	activeAnnotationId = $bindable(),
 	onAnnotationClick,
 	onTranscriptionDraw
@@ -86,6 +88,7 @@ let {
 			documentId={doc.id}
 			transcribeMode={transcribeMode}
 			blockNumbers={blockNumbers}
+			annotationReloadKey={annotationReloadKey}
 			bind:activeAnnotationId={activeAnnotationId}
 			onAnnotationClick={onAnnotationClick}
 			onTranscriptionDraw={onTranscriptionDraw}