feat(hero skill): add slot support for hero skill detail panel

1. 新增技能槽位参数，解决同底座技能（如普攻+触发技能）的分档定位问题
2. 新增2级/3级面板节点配置，自动隐藏无对应档位的面板
3. 重构英雄技能档位生成逻辑，支持按槽位精确查找技能配置
4. 优化技能弹窗渲染逻辑，传递槽位参数避免匹配错误分组

assets/resources/gui/element/SInfoBox.prefab

@@ -2293,12 +2293,18 @@
     "main_status": {
       "__id__": 67
     },
+    "lv2_node": {
+      "__id__": 85
+    },
     "lv2_status": {
       "__id__": 175
     },
     "lv2_desc": {
       "__id__": 191
     },
+    "lv3_node": {
+      "__id__": 110
+    },
     "lv3_status": {
       "__id__": 203
     },