fix: persist auth across refresh

frontend/src/lib/store.ts

@@ -19,13 +19,39 @@ interface AppState {
 	logout: () => void;
 }
 
+const initialUser =
+	typeof window !== "undefined"
+		? (() => {
+				const raw = localStorage.getItem("user");
+				return raw ? (JSON.parse(raw) as User) : null;
+			})()
+		: null;
+const initialToken =
+	typeof window !== "undefined" ? localStorage.getItem("token") : null;
+
 export const useStore = create<AppState>()((set) => ({
-	user: null,
-	token: null,
-	isAuthenticated: false,
-	setUser: (user) => set({ user, isAuthenticated: !!user }),
-	setToken: (token) => set({ token }),
+	user: initialUser,
+	token: initialToken,
+	isAuthenticated: !!initialToken,
+	setUser: (user) => {
+		if (typeof window !== "undefined") {
+			if (user) localStorage.setItem("user", JSON.stringify(user));
+			else localStorage.removeItem("user");
+		}
+		set({ user, isAuthenticated: !!user });
+	},
+	setToken: (token) => {
+		if (typeof window !== "undefined") {
+			if (token) localStorage.setItem("token", token);
+			else localStorage.removeItem("token");
+		}
+		set({ token, isAuthenticated: !!token });
+	},
 	logout: () => {
+		if (typeof window !== "undefined") {
+			localStorage.removeItem("user");
+			localStorage.removeItem("token");
+		}
 		set({ user: null, token: null, isAuthenticated: false });
 	},
 }));