refactor(class): 抽离攻克任务组件并优化样式与资源

1.  将ResolveProblemBox从class_update_widgets.dart抽离到公共组件目录
2.  替换静态渐变背景为CDN资源背景图，适配平板和手机端
3.  将点赞评论按钮的图标从内置Icons替换为本地png资源
4.  更新pubspec.yaml添加新的图片资源路径
5.  删除冗余的空行配置

lib/core/components/resolve_problem_box.dart

@@ -0,0 +1,117 @@
+import 'package:cached_network_image/cached_network_image.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_screenutil/flutter_screenutil.dart';
+import 'package:new_learn/core/utils/img_url.dart';
+import 'package:new_learn/core/utils/screen_adapt_template.dart';
+
+/// ============================================================
+/// 【ResolveProblemBox】攻克任务卡（对标 Vue ResolveProblem.vue）
+///
+/// 用于展示"刚刚攻克了 ｢xxx｣ 的所有高难考点"类提示。
+/// 由 class_update_widgets.dart 抽离，详情页也可复用。
+/// 背景图 + 云朵装饰走 CDN，与 Vue 版 $img('/StaticResource/...') 同源。
+/// ============================================================
+class ResolveProblemBox extends StatelessWidget {
+  const ResolveProblemBox({
+    super.key,
+    this.title = '刚刚攻克了',
+    required this.desc,
+  });
+
+  /// 标题（默认 "刚刚攻克了"）
+  final String title;
+
+  /// 攻克的知识点描述（如 "二次函数最值问题"）
+  final String desc;
+
+  @override
+  Widget build(BuildContext context) {
+    final isPad = MediaQuery.sizeOf(context).width >= AppAdapt.tabletBreakpoint;
+
+    final bgUrl = ImgUrl.build(
+      isPad
+          ? '/StaticResource/2026-06-02/resolve-bg2-pad1780388446390.png'
+          : '/StaticResource/2026-05-07/resolve-bg2.png',
+    );
+    final cloudUrl = ImgUrl.build(
+      isPad
+          ? '/StaticResource/2026-06-02/cloud-pad1780388443051.png'
+          : '/StaticResource/2026-05-07/cloud.png',
+    );
+
+    final cloudHeight = isPad ? 107.h : 74.h;
+
+    return Container(
+      width: double.infinity,
+      decoration: BoxDecoration(
+        borderRadius: BorderRadius.circular(10.r),
+        image: DecorationImage(
+          image: CachedNetworkImageProvider(bgUrl),
+          fit: BoxFit.fill,
+          alignment: Alignment.topCenter,
+        ),
+      ),
+      // 裁剪所有子元素到圆角内（对标 Vue overflow:hidden）
+      clipBehavior: Clip.antiAlias,
+      child: Stack(
+        // Stack 默认不裁剪 Positioned 子元素，必须显式设置
+        clipBehavior: Clip.hardEdge,
+        children: [
+          // 底部云朵装饰（贴底部，z-index 1）
+          Positioned(
+            left: 0,
+            right: 0,
+            bottom: 0,
+            child: CachedNetworkImage(
+              imageUrl: cloudUrl,
+              height: cloudHeight,
+              width: double.infinity,
+              fit: BoxFit.fitWidth,
+            ),
+          ),
+          // 文本层（padding 在云朵之上，z-index 2）
+          Padding(
+            padding: EdgeInsets.fromLTRB(19.w, 25.h, 19.w, 11.h),
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                Text(
+                  title,
+                  style: const TextStyle(
+                    fontSize: 15,
+                    fontWeight: FontWeight.w900,
+                    color: Color(0xFF1D2B47),
+                  ),
+                ),
+                SizedBox(height: 3.h),
+                Text.rich(
+                  TextSpan(
+                    children: [
+                      TextSpan(
+                        text: '｢$desc｣',
+                        style: const TextStyle(
+                          fontSize: 13,
+                          fontWeight: FontWeight.w500,
+                          color: Color(0xFF1D2B47),
+                        ),
+                      ),
+                      const TextSpan(
+                        text: ' 的所有高难考点！',
+                        style: TextStyle(
+                          fontSize: 13,
+                          fontWeight: FontWeight.w500,
+                          color: Color(0xFF45597E),
+                        ),
+                      ),
+                    ],
+                  ),
+                ),
+              ],
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}