code-review-fix task 11.4: add aria-pressed to span drawing and prediction toggle buttons

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

src/components/PredictionPanel.tsx

@@ -160,6 +160,7 @@ export default function PredictionPanel({
                 <label className="text-[10px] text-muted-foreground">Show on chart</label>
                 <button
                   onClick={onToggleVisibility}
+                  aria-pressed={visible}
                   className={`px-2 py-0.5 text-[10px] rounded transition-colors ${
                     visible
                       ? 'bg-primary/20 text-primary'