feat 搭建架构骨架

src/directives/index.ts

@@ -0,0 +1,12 @@
+import type { App } from 'vue'
+import lazy from './lazy'
+import debounce from './debounce'
+import throttle from './throttle'
+
+/** main.ts 调用：统一注册自定义指令 */
+export function setupDirectives(app: App): void {
+  app
+    .directive('lazy', lazy)
+    .directive('debounce', debounce)
+    .directive('throttle', throttle)
+}