feat: Add comprehensive documentation for Router Lists UI, including setup instructions, API endpoints, and frontend/backend structure; enhance navbar styles for better responsiveness

frontend/src/App.jsx

@@ -75,6 +75,7 @@ import {
   useLocation,
   Navigate
 } from 'react-router-dom';
+import { IconMenu2 } from '@tabler/icons-react';
 
 function App() {
   return (
@@ -208,6 +209,19 @@ function MainLayout() {
               <span className="fw-bold">S3 Lists Manager</span>
             </Link>
           </div>
+
+          {/* Кнопка бургера для мобильных */}
+          <button
+            className="navbar-toggler d-md-none"
+            type="button"
+            data-bs-toggle="collapse"
+            data-bs-target="#navbar-menu"
+            aria-controls="navbar-menu"
+            aria-expanded="false"
+            aria-label="Toggle navigation"
+          >
+            <IconMenu2 />
+          </button>
           
           {/* Основное меню */}
           <div className="collapse navbar-collapse" id="navbar-menu">
@@ -264,7 +278,7 @@ function MainLayout() {
           </div>
           
           {/* Правая часть навбара: язык и тема */}
-          <div className="navbar-nav flex-row order-md-last">
+          <div className="navbar-nav flex-row order-md-last ms-2">
             <div className="nav-item me-2">
               <select
                 className="form-select form-select-sm"