feat(battle): add silver and diamond reward system

1. 新增银币、钻石奖励配置到游戏结算配置表
2. 添加银币、钻石奖励的预制体与组件绑定
3. 实现结算逻辑：固定发放银币，按胜负区间随机发放钻石
4. 新增奖励UI展示条目，完整展示新增奖励类型

assets/resources/gui/element/reward_item_silver.prefab.meta

@@ -0,0 +1,13 @@
+{
+  "ver": "1.1.50",
+  "importer": "prefab",
+  "imported": true,
+  "uuid": "20ae7600-8171-4f6f-8acf-144ea69852c6",
+  "files": [
+    ".json"
+  ],
+  "subMetas": {},
+  "userData": {
+    "syncNodeName": "reward_item_silver"
+  }
+}