Use Vite env key for Gemini

vite.config.ts

@@ -1,16 +1,6 @@
-import { defineConfig, loadEnv } from 'vite';
+import { defineConfig } from 'vite';
 import react from '@vitejs/plugin-react';
 
-export default defineConfig(({ mode }) => {
-  // Load env file based on `mode` in the current working directory.
-  const env = loadEnv(mode, (process as any).cwd(), '');
-  
-  return {
-    plugins: [react()],
-    define: {
-      // This allows the app code to continue using process.env.API_KEY
-      // even though it is running in the browser.
-      'process.env.API_KEY': JSON.stringify(env.API_KEY)
-    }
-  };
+export default defineConfig({
+  plugins: [react()]
 });