feat(ui): add main menu and navigation skeleton

app/src/main/java/ru/project/App.java

@@ -1,10 +1,31 @@
 package ru.project;
 
-/**
- * Hello world!
- */
-public class App {
-    public static void main(String[] args) {
-        System.out.println("Hello World!");
+import com.googlecode.lanterna.gui2.MultiWindowTextGUI;
+import com.googlecode.lanterna.screen.Screen;
+import com.googlecode.lanterna.screen.TerminalScreen;
+import com.googlecode.lanterna.terminal.DefaultTerminalFactory;
+import ru.project.ui.MainMenu;
+import ru.project.ui.Navigator;
+
+public final class App {
+
+  private App() {}
+
+  public static void main(String[] args) throws Exception {
+    DefaultTerminalFactory factory = new DefaultTerminalFactory();
+
+    Screen screen = new TerminalScreen(factory.createTerminal());
+
+    screen.startScreen();
+
+    try {
+      MultiWindowTextGUI gui = new MultiWindowTextGUI(screen);
+
+      Navigator navigator = new Navigator(gui);
+
+      gui.addWindowAndWait(new MainMenu(navigator));
+    } finally {
+      screen.stopScreen();
     }
+  }
 }