feat: AuthContext, protected routes, admin page, fix VideoPlayer URL

frontend/src/context/AuthContext.tsx

@@ -0,0 +1,50 @@
+import { createContext, useContext, useState, useEffect, type ReactNode } from 'react';
+import { apiFetch } from '../lib/api';
+
+export interface User {
+  id: string;
+  email: string | null;
+  nickname: string;
+  subscriptionLevel?: number;
+}
+
+interface AuthContextValue {
+  user: User | null;
+  loading: boolean;
+  setUser: (u: User | null) => void;
+}
+
+const AuthContext = createContext<AuthContextValue | null>(null);
+
+interface MeResponse {
+  success: boolean;
+  data: { user: User };
+}
+
+export function AuthProvider({ children }: { children: ReactNode }) {
+  const [user, setUser] = useState<User | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    let cancelled = false;
+
+    apiFetch<MeResponse>('/auth/me')
+      .then((res) => { if (!cancelled) setUser(res.data.user); })
+      .catch(() => { if (!cancelled) setUser(null); })
+      .finally(() => { if (!cancelled) setLoading(false); });
+
+    return () => { cancelled = true; };
+  }, []);
+
+  return (
+    <AuthContext.Provider value={{ user, loading, setUser }}>
+      {children}
+    </AuthContext.Provider>
+  );
+}
+
+export function useAuthContext(): AuthContextValue {
+  const ctx = useContext(AuthContext);
+  if (!ctx) throw new Error('useAuthContext must be used inside AuthProvider');
+  return ctx;
+}