Add Main Menu UI, alien models & editor configs

Add VS Code workspace/launch/settings for Unity development and a new MainMenu scene/UI (uxml, uss, tss) with MainMenuController and related assets. Import two alien character FBX models (with generated .meta settings) and add folder metadata. Update Git LFS pointers for a Game Kit scene and add modifications to Game Kit Controller assets (World Canvas material and Save Camera render texture) and ProjectSettings/QualitySettings. These changes bring initial UI/menu assets and character models into the project and add editor tooling/config for easier development.

Assets/Game/Menus/MainMenu/MainMenu.uss

@@ -0,0 +1,54 @@
+/* 1. Fondo y Contenedor Principal */
+.main-container {
+    width: 100%;
+    height: 100%;
+    flex-grow: 1;
+    align-items: center; 
+    justify-content: center; 
+    background-color: #2b0057; 
+}
+
+/* 2. Título "Loco" */
+.game-title {
+    font-size: 120px;
+    color: #ffffff;
+    -unity-font-style: bold;
+    text-shadow: 5px 5px 0px #000000; 
+    margin-bottom: 50px;
+    rotate: -5deg; 
+}
+
+/* 3. Botones Base */
+.menu-button {
+    width: 300px;
+    height: 80px;
+    margin: 15px;
+    background-color: #ffffff;
+    border-radius: 40px; 
+    border-width: 6px;
+    border-color: #000000;
+    font-size: 40px;
+    -unity-font-style: bold;
+    color: #000000;
+    transition-property: scale, rotate, background-color;
+    transition-duration: 0.2s;
+    transition-timing-function: ease-out-back; 
+}
+
+/* 4. Estado Hover */
+.menu-button:hover {
+    scale: 1.1 1.1; 
+    rotate: 3deg;   
+    background-color: #ffec00; 
+    color: #2b0057;
+}
+
+/* 5. Estado Pressed */
+.menu-button:active {
+    scale: 0.95 0.95; 
+    background-color: #ff8800; 
+}
+
+/* Estilo botón Salir */
+.button-exit { border-color: #ff0044; }
+.button-exit:hover { background-color: #ffcccc; }