Update Vite configuration to use base path from environment and simplify proxy settings; adjust main entry point for BrowserRouter basename.

frontend/src/main.jsx

@@ -1,14 +1,13 @@
-import { StrictMode } from "react";
-import { createRoot } from "react-dom/client";
-import { BrowserRouter } from "react-router-dom";
+import { StrictMode } from 'react'
+import { createRoot } from 'react-dom/client'
+import { BrowserRouter } from 'react-router-dom'
+import App from './App.jsx'
+import './index.css'
 
-import "./index.css";
-import App from "./App.jsx";
-
-createRoot(document.getElementById("root")).render(
+createRoot(document.getElementById('root')).render(
   <StrictMode>
-    <BrowserRouter>
+    <BrowserRouter basename={import.meta.env.BASE_URL}>
       <App />
     </BrowserRouter>
-  </StrictMode>,
-);
+  </StrictMode>
+)

frontend/vite.config.js

@@ -2,31 +2,21 @@ import { defineConfig, loadEnv } from 'vite'
 import react from '@vitejs/plugin-react'
 import tailwindcss from '@tailwindcss/vite'
 
-// https://vite.dev/config/
 export default defineConfig(({ mode }) => {
   const env = loadEnv(mode, import.meta.dirname, '')
   const proxyTarget = env.VITE_API_PROXY_TARGET || 'http://localhost:8000'
+  const base = env.VITE_BASE_PATH || '/'
 
   return {
+    base,
     plugins: [react(), tailwindcss()],
     server: {
       host: true,
-      // Needed for HTTPS tunnels like ngrok during OAuth callback flows.
-      // We allow all hosts in dev to avoid host-blocking when ngrok URL rotates.
       allowedHosts: true,
       port: 5173,
       proxy: {
-        // El backend agrupa todo bajo /api (researchers, export, …).
-        // Con un único prefijo evitamos tener que mantener una entrada
-        // por router cada vez que se añada un endpoint nuevo.
-        '/api': {
-          target: proxyTarget,
-          changeOrigin: true,
-        },
-        '/health': {
-          target: proxyTarget,
-          changeOrigin: true,
-        },
+        '/api': { target: proxyTarget, changeOrigin: true },
+        '/health': { target: proxyTarget, changeOrigin: true },
       },
     },
   }