fix: route web auth through same origin

apps/web/src/lib/auth.server.ts

@@ -1,12 +1,8 @@
-import { env } from "@code/env/web";
 import { redirect } from "react-router";
 
 interface AuthLoaderData {
   readonly token: string | null;
 }
-
-const tokenUrl = new URL("/api/auth/convex/token", env.VITE_AUTH_URL);
-
 export const loadAuthToken = async (
   request: Request
 ): Promise<AuthLoaderData> => {
@@ -14,9 +10,12 @@ export const loadAuthToken = async (
   if (!cookie) {
     return { token: null };
   }
+  const tokenUrl = new URL(
+    "/api/auth/convex/token",
+    new URL(request.url).origin
+  );
 
   const headers = new Headers({ cookie });
-  headers.set("host", tokenUrl.host);
   const response = await fetch(tokenUrl, { headers });
   if (response.status === 401) {
     return { token: null };