fix: update ORCID_REDIRECT_URI and enhance OAuth callback handling

- Changed ORCID_REDIRECT_URI in docker-compose for updated ngrok URL.
- Allowed all hosts in vite.config.js to support HTTPS tunnels during OAuth flows.
- Improved handling of OAuth codes in AuthCallbackPage to prevent duplicate exchanges.
- Added function to fetch ORCID display names to enrich researcher data in API service.

frontend/vite.config.js

@@ -11,6 +11,9 @@ export default defineConfig(({ mode }) => {
     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, …).