fix(typography): distinguish the OpenType group label from its items

The group header and the toggle rows under it shared the same muted 11px
style, flattening the hierarchy. The OpenType features label is now
semibold surface text while items stay muted.

src/components/properties/TypographySection.vue

@@ -235,7 +235,11 @@ function featureEnabled(features: Array<{ tag: string; enabled: boolean }>, tag:
         />
       </PanelFieldGroup>
 
-      <PanelFieldGroup :label="panels.openTypeFeatures" class="mb-3">
+      <PanelFieldGroup
+        :label="panels.openTypeFeatures"
+        class="mb-3"
+        :ui="{ label: 'font-semibold text-surface' }"
+      >
         <div class="grid gap-2.5">
           <label
             v-for="feature in commonFeatures"