feat: 增加AI配置文件与TTS自动朗读，修复二级页面返回按钮与音频播放

kouyu_english/lib/features/review/review_page.dart

@@ -482,6 +482,14 @@ class _AdaptiveLessonPageState extends State<AdaptiveLessonPage> {
     final lesson = widget.state.cachedAdaptiveLesson;
     if (lesson == null) {
       return AppPage(
+        appBar: AppBar(
+          leading: IconButton(
+            icon: const Icon(Icons.arrow_back),
+            tooltip: "返回",
+            onPressed: widget.onFinished,
+          ),
+          title: const Text("AI 四技能补练"),
+        ),
         child: SpacedColumn(
           children: [
             const Eyebrow('AI 四技能补练'),
@@ -494,6 +502,14 @@ class _AdaptiveLessonPageState extends State<AdaptiveLessonPage> {
     final done = index >= lesson.tasks.length;
     if (done) {
       return AppPage(
+        appBar: AppBar(
+          leading: IconButton(
+            icon: const Icon(Icons.arrow_back),
+            tooltip: "返回",
+            onPressed: widget.onFinished,
+          ),
+          title: const Text("补练完成"),
+        ),
         child: SpacedColumn(
           children: [
             const Eyebrow('补练已完成'),
@@ -510,7 +526,14 @@ class _AdaptiveLessonPageState extends State<AdaptiveLessonPage> {
     final task = lesson.tasks[index];
     final showStimulus = task.skill != 'listening';
     return AppPage(
-      appBar: AppBar(title: Text('AI 补练 · ${index + 1}/4')),
+      appBar: AppBar(
+        leading: IconButton(
+          icon: const Icon(Icons.arrow_back),
+          tooltip: "返回",
+          onPressed: widget.onFinished,
+        ),
+        title: Text('AI 补练 · ${index + 1}/4'),
+      ),
       child: SpacedColumn(
         children: [
           Eyebrow('${_skillLabel(task.skill)} · 已审核教学内容'),