refactor: reorganize imports and improve error handling across components

frontend/src/context/AuthContextValue.ts

@@ -0,0 +1,16 @@
+import { createContext } from 'react';
+
+export interface User {
+  user_id: number;
+  role: string;
+}
+
+export interface AuthContextType {
+  user: User | null;
+  login: () => Promise<void>;
+  logout: () => void;
+  isAuthenticated: boolean;
+  isLoading: boolean;
+}
+
+export const AuthContext = createContext<AuthContextType | undefined>(undefined);