feat: add Vue2 exercises for dynamic styles, lifecycle methods, component communication, and course management dashboard

- Implement dynamic styles and event handling in Vue2 with a card component.
- Create lifecycle methods exercise to simulate async data loading and instance destruction.
- Develop a component communication exercise with props, events, and slots.
- Build a comprehensive course management dashboard with filtering, statistics, and component interactions.

07-vue2/05-computed-and-watch/README.md

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+# 练习 5：computed 和 watch
+
+## 目标
+
+学会区分“根据已有数据推导结果”和“监听变化做额外动作”。
+
+## 你要练什么
+
+- `computed`
+- `watch`
+- 数据推导
+- 监听输入变化
+
+## 任务
+
+请基于页面结构完成以下操作：
+
+- 根据关键字过滤课程列表
+- 用 `computed` 计算过滤结果数量
+- 用 `watch` 在关键字变化时输出日志
+
+## 文件
+
+- [starter.html](/Users/lijiaqing/home/wwwroot/front-end-example/07-vue2/05-computed-and-watch/starter.html)
+- [starter.js](/Users/lijiaqing/home/wwwroot/front-end-example/07-vue2/05-computed-and-watch/starter.js)
+- [answer.html](/Users/lijiaqing/home/wwwroot/front-end-example/07-vue2/05-computed-and-watch/answer.html)
+- [answer.js](/Users/lijiaqing/home/wwwroot/front-end-example/07-vue2/05-computed-and-watch/answer.js)