fix(auth): defer guest login until chat entry

src/app/chat/chat-screen.tsx

@@ -3,7 +3,7 @@
 import { useEffect, useRef, useState } from "react";
 import Image from "next/image";
 
-import { useAuthState } from "@/stores/auth/auth-context";
+import { useAuthDispatch, useAuthState } from "@/stores/auth/auth-context";
 import { useChatDispatch, useChatState } from "@/stores/chat/chat-context";
 import { useUserState } from "@/stores/user/user-context";
 import { ROUTES } from "@/router/routes";
@@ -42,6 +42,7 @@ export function ChatScreen() {
   const state = useChatState();
   const chatDispatch = useChatDispatch();
   const authState = useAuthState();
+  const authDispatch = useAuthDispatch();
   const userState = useUserState();
   const navigator = useAppNavigator();
   const [showExternalBrowserDialog, setShowExternalBrowserDialog] =
@@ -70,6 +71,25 @@ export function ChatScreen() {
   const shouldShowPwaInstall = state.historyLoaded && state.messages.length >= 10;
 
   const externalBrowserPromptShownRef = useRef(false);
+  const guestLoginRequestedRef = useRef(false);
+
+  useEffect(() => {
+    if (!authState.hasInitialized || authState.isLoading) return;
+
+    if (authState.loginStatus !== "notLoggedIn") {
+      guestLoginRequestedRef.current = false;
+      return;
+    }
+
+    if (guestLoginRequestedRef.current) return;
+    guestLoginRequestedRef.current = true;
+    authDispatch({ type: "AuthGuestLoginSubmitted" });
+  }, [
+    authDispatch,
+    authState.hasInitialized,
+    authState.isLoading,
+    authState.loginStatus,
+  ]);
 
   useEffect(() => {
     if (