feat: Add Vue3 exercises and interview plan

- Introduced Vue3 exercises covering composable API, reactivity, lifecycle hooks, and built-in components.
- Added structured interview plan for frontend candidates focusing on HTML, CSS, JavaScript, TypeScript, and Vue.
- Included starter files for each exercise and detailed README documentation for guidance.

08-vue3/07-composable-and-async/starter.js

@@ -0,0 +1,38 @@
+const { createApp, ref, onMounted } = Vue;
+
+function useCourses() {
+  const courses = ref([]);
+  const loading = ref(true);
+  const error = ref("");
+
+  async function loadCourses() {
+    // 任务：
+    // 1. 模拟异步请求
+    // 2. 成功时给 courses 赋值
+    // 3. 失败时给 error 赋值
+    // 4. 最后把 loading 设为 false
+  }
+
+  return {
+    courses,
+    loading,
+    error,
+    loadCourses,
+  };
+}
+
+createApp({
+  setup() {
+    const { courses, loading, error, loadCourses } = useCourses();
+
+    onMounted(() => {
+      // 任务：页面挂载后调用 loadCourses
+    });
+
+    return {
+      courses,
+      loading,
+      error,
+    };
+  },
+}).mount("#app");