Add centralized API client with axios interceptors, remove vue-axios

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/types/vue.d.ts

@@ -1,15 +1 @@
-import { AxiosInstance } from 'axios';
 import { App } from 'vue';
-
-declare module '@vue/runtime-core' {
-  interface ComponentCustomProperties {
-    $http: AxiosInstance;
-  }
-}
-
-// 將類型擴展到 Vue 應用實例
-declare module 'vue' {
-  interface App {
-    $http: AxiosInstance;
-  }
-}