feat: add speech audio files and configuration for Jeff and Fireball

- Add 22 new MP3 speech files for characters Jeff and Fireball
- Update public/data/opponents.json to include speech arrays for both characters
- Each character now has intro, happy, and upset speech categories with 2-5 variations

public/data/opponents.json

@@ -153,7 +153,27 @@
       "id": "jeff",
       "spriteIndex": 6,
       "name": "Jeff",
-      "bio": "I play slow, I win fast!"
+      "bio": "I play slow, I win fast!",
+      "speech": {
+        "intro": [
+          "jeff-intro-01",
+          "jeff-intro-02"
+        ],
+        "happy": [
+          "jeff-happy-01",
+          "jeff-happy-02",
+          "jeff-happy-03",
+          "jeff-happy-04",
+          "jeff-happy-05"
+        ],
+        "upset": [
+          "jeff-upset-01",
+          "jeff-upset-02",
+          "jeff-upset-03",
+          "jeff-upset-04",
+          "jeff-upset-05"
+        ]
+      }
     },
     {
       "id": "gerome",
@@ -165,7 +185,27 @@
       "id": "fireball",
       "spriteIndex": 8,
       "name": "Fireball",
-      "bio": "Come on let's play! I promise not to use my x-ray eyes."
+      "bio": "Come on let's play! I promise not to use my x-ray eyes.",
+      "speech": {
+        "intro": [
+          "fireball-intro-01",
+          "fireball-intro-02"
+        ],
+        "happy": [
+          "fireball-happy-01",
+          "fireball-happy-02",
+          "fireball-happy-03",
+          "fireball-happy-04",
+          "fireball-happy-05"
+        ],
+        "upset": [
+          "fireball-upset-01",
+          "fireball-upset-02",
+          "fireball-upset-03",
+          "fireball-upset-04",
+          "fireball-upset-05"
+        ]
+      }
     },
     {
       "id": "bernie",