feat: Migrate to Nuxt 3 framework (#5184)

Co-authored-by: Michael Genson <71845777+michael-genson@users.noreply.github.com>
Co-authored-by: Kuchenpirat <24235032+Kuchenpirat@users.noreply.github.com>

frontend/server/api/[...].ts

@@ -0,0 +1,12 @@
+import { joinURL } from "ufo";
+
+export default defineEventHandler(async (event) => {
+  const apiUrl = useRuntimeConfig().apiUrl; // 'http://localhost:9000'
+
+  const target = joinURL(apiUrl, event.path);
+  if (event.path === "/api/auth/oauth") {
+    return sendRedirect(event, target); // redirect to BE for Oauth login
+  }
+
+  return proxyRequest(event, target);
+});