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-vue2/01-vue-instance-and-data/answer.js

@@ -0,0 +1,14 @@
+new Vue({
+  el: "#app",
+  data: {
+    title: "Vue2 基础入门",
+    lessonCount: 8,
+    learnerCount: 12,
+  },
+  methods: {
+    increaseLearner() {
+      this.learnerCount += 1;
+      console.log("当前学习人数：", this.learnerCount);
+    },
+  },
+});