feat(lst): tan stack routes added with protected routes

frontend/src/utils/auth.ts

@@ -0,0 +1,11 @@
+export function isAuthenticated() {
+    return localStorage.getItem("isAuthenticated") === "true";
+}
+
+export function signIn() {
+    return localStorage.setItem("isAuthenticated", "true");
+}
+
+export function signOut() {
+    return localStorage.removeItem("isAuthenticated");
+}