初始提交：姜十三论坛 Jiang13 Forum

轻量自用论坛，Go 单二进制 + React SPA 内嵌 + SQLite。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/hooks/useAuth.tsx

@@ -0,0 +1,47 @@
+import { createContext, useContext, useEffect, useState, useCallback, ReactNode } from 'react';
+import { api } from '../api/client';
+import type { User } from '../api/types';
+
+interface AuthCtx {
+  user: User | null;
+  loading: boolean;
+  refresh: () => Promise<void>;
+  logout: () => Promise<void>;
+}
+
+const AuthContext = createContext<AuthCtx>({
+  user: null, loading: true,
+  refresh: async () => {}, logout: async () => {},
+});
+
+export function AuthProvider({ children }: { children: ReactNode }) {
+  const [user, setUser] = useState<User | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  const refresh = useCallback(async () => {
+    try {
+      const data = await api.me();
+      setUser(data.user ?? null);
+    } catch {
+      setUser(null);
+    } finally {
+      setLoading(false);
+    }
+  }, []);
+
+  // 初始化只拉一次用户信息
+  useEffect(() => { refresh(); }, [refresh]);
+
+  const logout = async () => {
+    await api.logout();
+    setUser(null);
+  };
+
+  return (
+    <AuthContext.Provider value={{ user, loading, refresh, logout }}>
+      {children}
+    </AuthContext.Provider>
+  );
+}
+
+export const useAuth = () => useContext(AuthContext);