feat: 完善听力口语辅助状态记录、练习分块与复习抽查间隔机制

kouyu_english/lib/widgets/usage_card.dart

@@ -37,7 +37,8 @@ class UsageCard extends StatelessWidget {
     if (usage == null) return const SizedBox.shrink();
     final lines = <({String label, String text})>[
       if (usage.when.isNotEmpty) (label: '什么时候用', text: usage.when),
-      if (!compact && usage.reply.isNotEmpty) (label: '对方会怎么答', text: usage.reply),
+      if (!compact && usage.reply.isNotEmpty)
+        (label: '对方会怎么答', text: usage.reply),
       if (!compact && usage.swap.isNotEmpty) (label: '换个说法', text: usage.swap),
       // Mid-exercise only the nearest confusion is worth a line; the full
       // list belongs on the preview and lookup cards.
@@ -57,10 +58,9 @@ class UsageCard extends StatelessWidget {
           for (final line in lines)
             RichText(
               text: TextSpan(
-                style: DefaultTextStyle.of(context).style.copyWith(
-                  color: AppColors.warmInk,
-                  height: 1.45,
-                ),
+                style: DefaultTextStyle.of(
+                  context,
+                ).style.copyWith(color: AppColors.warmInk, height: 1.45),
                 children: [
                   TextSpan(
                     text: '${line.label}：',
@@ -94,7 +94,10 @@ class SegmentUsage extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final ids = findLessonSegment(segmentId)?.targetItemIds ?? const <String>[];
-    final explained = [for (final id in ids) if (coreUsage(id) != null) id];
+    final explained = [
+      for (final id in ids)
+        if (coreUsage(id) != null) id,
+    ];
     if (explained.isEmpty) return const SizedBox.shrink();
     return SpacedColumn(
       spacing: 8,