feat: add access token management and gateway token exchange functionality

app/gateway-frontend/src/env.d.ts

@@ -5,3 +5,11 @@ declare module '*.vue' {
     const component: DefineComponent<{}, {}, any>;
     export default component;
 }
+
+interface ImportMetaEnv {
+    readonly VITE_GAME_WEB_URL?: string;
+}
+
+interface ImportMeta {
+    readonly env: ImportMetaEnv;
+}