feat: 新增水球技能并调整英雄技能配置

- 新增水球技能资源文件、动画及配置项
- 调整盾战士、圣骑士、牧师等英雄的技能触发条件
- 更新技能说明文档，补充攻击类型和特殊效果描述
- 微调技能准备动画的垂直位置
- 为护盾buff动画添加新的精灵帧序列

assets/resources/game/skill/ready/up_blue.prefab

@@ -87,7 +87,7 @@
     "_lpos": {
       "__type__": "cc.Vec3",
       "x": 0,
-      "y": 10,
+      "y": -7.953,
       "z": 0
     },
     "_lrot": {

assets/resources/game/skill/ready/up_green.prefab

@@ -87,7 +87,7 @@
     "_lpos": {
       "__type__": "cc.Vec3",
       "x": 0,
-      "y": 10,
+      "y": -5.121,
       "z": 0
     },
     "_lrot": {

assets/resources/game/skill/ready/up_red.prefab

@@ -87,7 +87,7 @@
     "_lpos": {
       "__type__": "cc.Vec3",
       "x": 0,
-      "y": 10,
+      "y": -7.795,
       "z": 0
     },
     "_lrot": {