fix(setup): update env.ts file

Author: shreeyash07

env.ts

@@ -5,4 +5,5 @@ import {
 
 export default defineConfig({
     APP_TITLE: Schema.string(),
+    APP_UNIFIED_ENDPOINT: Schema.string.optional(),
 });

src/utils/restRequest/unified.ts

@@ -3,7 +3,7 @@ import { ContextInterface } from '@togglecorp/toggle-request';
 import { resolveUrl } from '#utils/resolveUrl';
 
 const CONTENT_TYPE_JSON = 'application/json';
-const unifiedApi = process.env.UNIFIED_ENDPOINT ?? '';
+const unifiedApi = import.meta.env.APP_UNIFIED_ENDPOINT ?? '';
 
 type ResponseError = {
     status: number;