🔧(frontend) pass API and LiveKit server URLs through environment vars

Configured the frontend to use environment variables (prefixed with "VITE_") for API
and LiveKit server URLs, which will be overridden in the Helm chart values
to ensure correct URLs are used in different environments.

src/frontend/.env.development

@@ -0,0 +1,2 @@
+VITE_API_BASE_URL=http://localhost:8071/api/v1.0/
+VITE_LIVEKIT_SERVER_URL=http://localhost:7880

src/frontend/src/App.tsx

@@ -4,8 +4,8 @@ import {LiveKitRoom, VideoConference} from "@livekit/components-react";
 
 import '@livekit/components-styles';
 
-const API_BASE_URL = 'http://localhost:8071/api/v1.0/'
-const LIVEKIT_SERVER_URL = 'http://localhost:7880'
+const API_BASE_URL = import.meta.env.VITE_API_BASE_URL
+const LIVEKIT_SERVER_URL = import.meta.env.VITE_LIVEKIT_SERVER_URL
 
 export interface User {
   id: string;

src/frontend/src/vite-env.d.ts

@@ -1 +1,9 @@
 /// <reference types="vite/client" />
+interface ImportMetaEnv {
+  readonly VITE_API_BASE_URL: string;
+  readonly VITE_LIVEKIT_SERVER_URL: string;
+}
+
+interface ImportMeta {
+  readonly env: ImportMetaEnv;
+}