feat: Implement Game Type selection step

- Adds the 'GameTypeStep' to the new game wizard.
- Features large, touch-friendly buttons for selecting game types.
- Selection automatically proceeds to the next step.
- Includes progress indicator and back navigation.
- Closes #9

src/components/NewGame.module.css

@@ -188,4 +188,31 @@
 .clear-input-btn:active, .clear-input-btn:focus {
     color: #fff;
     outline: none;
+}
+.game-type-selection {
+    display: grid;
+    grid-template-columns: 1fr 1fr;
+    gap: 16px;
+    width: 100%;
+    margin: 16px 0;
+}
+.game-type-btn {
+    background: #2a2a2a;
+    border: 2px solid #333;
+    color: #fff;
+    font-size: 1.4rem;
+    font-weight: 600;
+    padding: 24px;
+    border-radius: 8px;
+    cursor: pointer;
+    text-align: center;
+    transition: background 0.2s, border-color 0.2s;
+}
+.game-type-btn:hover {
+    background: #333;
+    border-color: #555;
+}
+.game-type-btn.selected {
+    background: #4a4a4a;
+    border-color: #777;
 }