refactor(HInfoComp): 简化卡牌等级显示逻辑

1. 将lv_node从Node改为Label类型，直接通过string属性更新等级文本
2. 移除原有的子节点遍历匹配逻辑，替换为更简洁的文本赋值方式
3. 新增pool_lv_node节点属性用于后续池等级相关逻辑
4. 同步更新了ha2.prefab的预制体结构与meta配置文件

assets/resources/game/heros/ha2.prefab

@@ -47,13 +47,10 @@
       },
       {
         "__id__": 53
-      },
-      {
-        "__id__": 55
       }
     ],
     "_prefab": {
-      "__id__": 57
+      "__id__": 55
     },
     "_lpos": {
       "__type__": "cc.Vec3",
@@ -898,32 +895,6 @@
     "__type__": "cc.CompPrefabInfo",
     "fileId": "23j+p5lLdC+r4iKSVeLNM4"
   },
-  {
-    "__type__": "cc.Animation",
-    "_name": "",
-    "_objFlags": 0,
-    "__editorExtras__": {},
-    "node": {
-      "__id__": 1
-    },
-    "_enabled": true,
-    "__prefab": {
-      "__id__": 56
-    },
-    "playOnLoad": false,
-    "_clips": [
-      {
-        "__uuid__": "cd3e0604-8840-4794-8755-f2ed86dbe264",
-        "__expectedType__": "cc.AnimationClip"
-      }
-    ],
-    "_defaultClip": null,
-    "_id": ""
-  },
-  {
-    "__type__": "cc.CompPrefabInfo",
-    "fileId": "49+IQe4gZPPYzJ/FgxeX/O"
-  },
   {
     "__type__": "cc.PrefabInfo",
     "root": {