fix auth

.env.example

@@ -31,5 +31,9 @@ DEFAULT_EMBEDDING_DIM=0
 DEFAULT_EMBEDDING_REQUEST_TIMEOUT=60
 
 # === Frontend ===
-VITE_API_URL=http://localhost:8000
+# Vite dev-server proxy target — INSIDE the frontend container "localhost" is
+# the container itself, so docker-compose defaults this to http://backend:8000
+# (the service name). Override only if you run vite outside docker against a
+# host backend (in which case use http://localhost:8000).
+API_PROXY_TARGET=http://backend:8000
 FRONTEND_BUILD_TARGET=dev