feat: 新增全局确认弹窗、多页面UI优化与网络日志开关

1.  新增全局二次确认弹窗组件confirm_box，支持自定义参数并对标小程序实现
2.  优化班级板块多处UI：
    - 修复point_rank_view中Web端字体溢出问题，使用FittedBox自适应缩放
    - 重构class_update_widgets的PostCard，新增卡片背景控制开关并替换光晕实现
    - 优化class_update_view的在线同学栏与头像组布局，支持动态计算展示数量
    - 调整my_update_detail_page的评论区结构，修复评论高亮与删除浮层定位问题
3.  为dio_client新增网络日志总开关，可按需开启请求响应打印
4.  修复多处代码格式与注释细节问题

lib/features/class/class_update_view.dart

@@ -330,7 +330,7 @@ class _ClassUpdateViewState extends ConsumerState<ClassUpdateView> {
     return Container(
       height: 58.h,
       margin: EdgeInsets.fromLTRB(14.w, 12.h, 14.w, 15.h),
-      padding: EdgeInsets.fromLTRB(2.w, 2.h, 5.w, 2.h),
+      // padding: EdgeInsets.fromLTRB(2.w, 2.h, 5.w, 2.h),
       decoration: BoxDecoration(
         image: DecorationImage(
           image: CachedNetworkImageProvider(
@@ -339,12 +339,30 @@ class _ClassUpdateViewState extends ConsumerState<ClassUpdateView> {
           fit: BoxFit.fill,
         ),
       ),
-      child: Row(
+      child: Stack(
+        fit: StackFit.expand,
         children: [
-          _buildOnlineLeft(),
-          const Spacer(),
-          _buildAvatarStack(),
-          _buildAllButton(),
+          LayoutBuilder(
+            builder: (context, rowConstraints) {
+              final rowWidth = rowConstraints.maxWidth;
+              return Row(
+                children: [
+                  _buildOnlineLeft(),
+                  Expanded(
+                    // 占据剩余空间，把真实可用宽度传给头像组动态计算数量
+                    child: LayoutBuilder(
+                      builder: (context, constraints) =>
+                          _buildAvatarStack(constraints.maxWidth, rowWidth),
+                    ),
+                  ),
+                  // 预留「全部」按钮宽度（按钮已悬浮于右上角，不在 Row 内占位）
+                  SizedBox(width: 62.w),
+                ],
+              );
+            },
+          ),
+          // 「全部」按钮：悬浮右上角（对标 Vue position: absolute; top/right: 2rpx）
+          Positioned(top: 1, right: 1, child: _buildAllButton()),
         ],
       ),
     );
@@ -354,7 +372,38 @@ class _ClassUpdateViewState extends ConsumerState<ClassUpdateView> {
     return Row(
       children: [
         SizedBox(width: 15.w),
-        const Text('在线同学', style: TextStyle(fontSize: 14, color: _titleColor)),
+        // 「在线同学」底部渐变高亮条（对标 Vue 的 linear-gradient 下划线）
+        // clipBehavior: Clip.none 允许渐变条溢出 Stack 边界（bottom 为负值时不被裁剪）
+        Stack(
+          clipBehavior: Clip.none,
+          children: [
+            Positioned(
+              left: 0,
+              bottom: -4,
+              child: Container(
+                width: 59.5.w,
+                height: 9.h,
+                decoration: BoxDecoration(
+                  borderRadius: BorderRadius.circular(50.r),
+                  gradient: const LinearGradient(
+                    begin: Alignment.centerLeft,
+                    end: Alignment.centerRight,
+                    stops: [0, 0.3578, 1],
+                    colors: [
+                      Color(0x808AECFD), // rgba(138,236,253,0.5)
+                      Color(0x331D9CFF), // rgba(29,156,255,0.2)
+                      Color(0x003D7DF5), // rgba(61,125,245,0)
+                    ],
+                  ),
+                ),
+              ),
+            ),
+            const Text(
+              '在线同学',
+              style: TextStyle(fontSize: 14, color: _titleColor),
+            ),
+          ],
+        ),
         SizedBox(width: 5.w),
         Text(
           '$_onlineCount',
@@ -370,30 +419,40 @@ class _ClassUpdateViewState extends ConsumerState<ClassUpdateView> {
     );
   }
 
-  /// 头像组：在线在前、离线在后，最多展示 6 个
-  Widget _buildAvatarStack() {
-    final urls = _avatarUrls.take(6).toList();
-    if (urls.isEmpty) return const SizedBox.shrink();
+  /// 头像组：在线在前、离线在后，数量按剩余宽度动态计算（对标 Vue updateAvatarMaxCount，最多 20）
+  /// 可用宽度限制在右侧背景块内（对标 Vue 左区 40% + 44rpx 内边距）：
+  /// 左界 = 行宽 40% + 22px，右界 = 「全部」按钮左缘；同时不超过文字右侧空间，避免压住文字
+  Widget _buildAvatarStack(double maxWidth, double rowWidth) {
     final size = 25.w;
     final overlap = size * 0.94;
-    return SizedBox(
-      width: size + (urls.length - 1) * overlap,
-      height: size,
-      child: Stack(
-        children: [
-          for (int i = 0; i < urls.length; i++)
-            Positioned(
-              left: i * overlap,
-              child: GestureDetector(
-                // 点头像 → 大图预览单张
-                onTap: () => ImagePreviewViewer.showSingle(
-                  context,
-                  imageProvider: CachedNetworkImageProvider(urls[i]),
+    // 0.6 行宽 − 22px 左间距 − 62px 按钮宽
+    final rightBlockAvail = rowWidth * 0.6 - 84.w;
+    final avail = maxWidth < rightBlockAvail ? maxWidth : rightBlockAvail;
+    // 首个占满 size，后续每个只前进 overlap
+    final fitCount = avail >= size ? ((avail - size) / overlap).floor() + 1 : 0;
+    final urls = _avatarUrls.take(fitCount > 20 ? 20 : fitCount).toList();
+    if (urls.isEmpty) return const SizedBox.shrink();
+    return Align(
+      alignment: Alignment.centerRight,
+      child: SizedBox(
+        width: size + (urls.length - 1) * overlap,
+        height: size,
+        child: Stack(
+          children: [
+            for (int i = 0; i < urls.length; i++)
+              Positioned(
+                left: i * overlap,
+                child: GestureDetector(
+                  // 点头像 → 大图预览单张
+                  onTap: () => ImagePreviewViewer.showSingle(
+                    context,
+                    imageProvider: CachedNetworkImageProvider(urls[i]),
+                  ),
+                  child: UserCircleAvatar(url: urls[i], radius: size / 2),
                 ),
-                child: UserCircleAvatar(url: urls[i], radius: size / 2),
               ),
-            ),
-        ],
+          ],
+        ),
       ),
     );
   }
@@ -404,7 +463,7 @@ class _ClassUpdateViewState extends ConsumerState<ClassUpdateView> {
       onTap: () => context.push('/class/all-student'),
       child: Container(
         width: 62.w,
-        height: 34.h,
+        height: 33.5.h,
         alignment: Alignment.center,
         decoration: BoxDecoration(
           gradient: const LinearGradient(
@@ -412,10 +471,32 @@ class _ClassUpdateViewState extends ConsumerState<ClassUpdateView> {
             end: Alignment.bottomCenter,
             colors: [Color(0xFF3D7DF5), Color(0xFF3C84FF), Color(0xFF8AD1FD)],
           ),
+          // 对标 Vue border-radius: 0 30rpx 0 40rpx（右上 15 / 左下 20，其余直角）
           borderRadius: BorderRadius.only(
             topRight: Radius.circular(15.r),
-            bottomLeft: Radius.circular(15.r),
-            bottomRight: Radius.circular(20.r),
+            bottomLeft: Radius.circular(20.r),
+          ),
+          // 对标 Vue box-shadow 外层：0 15rpx 11.3rpx rgba(61,125,245,0.08)
+          boxShadow: const [
+            BoxShadow(
+              color: Color(0x143D7DF5),
+              offset: Offset(0, 7.5),
+              blurRadius: 5.65,
+            ),
+          ],
+        ),
+        // 对标 Vue box-shadow 内层 inset 0 2rpx 18.4rpx rgba(183,236,255,0.56)
+        // Flutter 无内阴影，用顶部渐变近似（浅蓝光晕从顶边向下淡出）
+        foregroundDecoration: BoxDecoration(
+          borderRadius: BorderRadius.only(
+            topRight: Radius.circular(15.r),
+            bottomLeft: Radius.circular(20.r),
+          ),
+          gradient: const LinearGradient(
+            begin: Alignment.topCenter,
+            end: Alignment.bottomCenter,
+            stops: [0, 0.3],
+            colors: [Color(0x8FB7ECFF), Color(0x00B7ECFF)],
           ),
         ),
         child: Row(