Remove default category selection in favor of a hint prompt

- Drop the `_lastCategory` module-level state and the logic that pre-selected a tab on scene entry.
- Show a "Select a category above to see its games" hint instead, destroyed once the user picks a category.

src/scenes/GameMenuScene.js

@@ -6,8 +6,6 @@ import { addFullscreenButton } from '../ui/FullscreenButton.js';
 import { playMenuMusic, stopMenuMusic } from '../ui/MenuMusic.js';
 import { TutorialModal } from '../ui/TutorialModal.js';
 
-let _lastCategory = null;
-
 const CATEGORIES = [
   { key: 'tabletop', label: 'Tabletop' },
   { key: 'cards', label: 'Cards & Dice' },
@@ -107,14 +105,16 @@ export default class GameMenuScene extends Phaser.Scene {
       this._tabIcons[key] = icon;
     });
 
-    const startKey = allActiveCats.find(c => c.key === _lastCategory) ? _lastCategory : allActiveCats[0].key;
-    this.showCategory(startKey);
+    // No category is selected by default — the user picks one to see games.
+    this._hintText = this.add.text(cx, 540, 'Select a category above to see its games', {
+      fontSize: '26px', color: COLORS.mutedHex,
+    }).setOrigin(0.5);
 
     new Button(this, cx, GAME_HEIGHT - 60, 'Back', () => this.scene.start('Landing'), { variant: 'ghost' });
   }
 
   showCategory(key) {
-    _lastCategory = key;
+    if (this._hintText) { this._hintText.destroy(); this._hintText = null; }
     for (const [k, btn] of Object.entries(this._tabs)) {
       btn.setActive(k === key);
     }