feat(auth): enhance logout and login flow with return URL handling

frontend/src/router/router.js

@@ -94,6 +94,7 @@ const routes = [
     name: 'login',
     component: LoginView,
     meta: { notAuthenticated: true },
+    props: (route) => ({ returnUrl: route.query.returnUrl || '/landing' })
   },
   {
     path: '/profile',
@@ -119,11 +120,20 @@ router.beforeEach((to, from, next) => {
   const authStore = useAuthStore();
 
   if (to.matched.some((record) => record.meta.requiresAuth)) {
-    if (!authStore.isAuthenticated) next({ name: 'login' });
+    if (!authStore.isAuthenticated) {
+      next({ 
+        name: 'login',
+        query: { returnUrl: to.fullPath }
+      });
+    } else {
+      next();
+    }
   } else if (to.matched.some((record) => record.meta.notAuthenticated)) {
     if (authStore.isAuthenticated) next({ name: 'landing' });
+    else next();
+  } else {
+    next();
   }
-  next();
 });
 
 export default router;