feat: add Nadia and Smasher opponents with full media assets

- Add sprite images, speech audio, and animation videos for Nadia and
  The Smasher opponents
- Update opponents.json with new character definitions and speech cues
- Fix 2048 UI: reposition buttons and add Leave button

public/data/opponents.json

@@ -558,6 +558,64 @@
           "blackwind-pick"
         ]
       }
+    },
+    {
+      "id": "nadia",
+      "spriteIndex": 20,
+      "name": "Nadia",
+      "bio": "She's here from the future to learn our games and study our culture.",
+      "speech": {
+        "intro": [
+          "nadia-intro-01",
+          "nadia-intro-02"
+        ],
+        "happy": [
+          "nadia-happy-01",
+          "nadia-happy-02",
+          "nadia-happy-03",
+          "nadia-happy-04",
+          "nadia-happy-05"
+        ],
+        "upset": [
+          "nadia-upset-01",
+          "nadia-upset-02",
+          "nadia-upset-03",
+          "nadia-upset-04",
+          "nadia-upset-05"
+        ],
+        "pick": [
+          "nadia-pick"
+        ]
+      }
+    },
+    {
+      "id": "smasher",
+      "spriteIndex": 19,
+      "name": "The Smasher",
+      "bio": "Oooooooh yeah brother!!! You wanna play with The Smasher?!",
+      "speech": {
+        "intro": [
+          "smasher-intro-01",
+          "smasher-intro-02"
+        ],
+        "happy": [
+          "smasher-happy-01",
+          "smasher-happy-02",
+          "smasher-happy-03",
+          "smasher-happy-04",
+          "smasher-happy-05"
+        ],
+        "upset": [
+          "smasher-upset-01",
+          "smasher-upset-02",
+          "smasher-upset-03",
+          "smasher-upset-04",
+          "smasher-upset-05"
+        ],
+        "pick": [
+          "smasher-pick"
+        ]
+      }
     }
   ]
 }

public/src/games/2048/2048Game.js

@@ -117,8 +117,9 @@ export default class Game2048 extends Phaser.Scene {
       fontFamily: FONT_TITLE, fontSize: '44px', color: COLORS.textHex,
     }).setOrigin(0.5, 0).setDepth(D.ui);
 
-    new Button(this, GAME_WIDTH - 270, 65, 'New Game', () => this._newGame(), { variant: 'ghost', width: 200, height: 54, fontSize: 22 }).setDepth(D.ui);
-    new Button(this, GAME_WIDTH - 60,  65, 'Theme',    () => this._showSchemePicker(), { variant: 'ghost', width: 110, height: 54, fontSize: 22 }).setDepth(D.ui);
+    new Button(this, GAME_WIDTH - 270, 165, 'New Game', () => this._newGame(), { variant: 'ghost', width: 200, height: 54, fontSize: 22 }).setDepth(D.ui);
+    new Button(this, GAME_WIDTH - 60,  165, 'Theme',    () => this._showSchemePicker(), { variant: 'ghost', width: 110, height: 54, fontSize: 22 }).setDepth(D.ui);
+    new Button(this, GAME_WIDTH - 60, GAME_HEIGHT - 60, 'Leave', () => this.scene.start('GameMenu'), { variant: 'ghost', width: 110, height: 54, fontSize: 22 }).setDepth(D.ui);
   }
 
   _drawScoreBox(x, y, label) {