fix(chat): hydrate user avatar after auth restore

src/stores/user/user-auth-sync.tsx

@@ -0,0 +1,34 @@
+"use client";
+
+/**
+ * Auth → User 启动同步器
+ *
+ * AuthStatusChecker 只负责恢复 loginStatus；头像等登录用户资料由
+ * UserStorage 持久化在 user machine 这一侧。冷启动直达 /chat 时，
+ * 没有经过 splash/auth 的跳转副作用，因此需要在登录态恢复后主动
+ * hydrate user store。
+ */
+import { useEffect, useRef } from "react";
+
+import { useAuthState } from "@/stores/auth/auth-context";
+
+import { useUserDispatch } from "./user-context";
+
+export function UserAuthSync() {
+  const { loginStatus } = useAuthState();
+  const userDispatch = useUserDispatch();
+  const lastInitializedStatusRef = useRef<string | null>(null);
+
+  useEffect(() => {
+    if (loginStatus === "notLoggedIn" || loginStatus === "guest") {
+      lastInitializedStatusRef.current = null;
+      return;
+    }
+
+    if (lastInitializedStatusRef.current === loginStatus) return;
+    lastInitializedStatusRef.current = loginStatus;
+    userDispatch({ type: "UserInit" });
+  }, [loginStatus, userDispatch]);
+
+  return null;
+}