refactor(skill): 清理旧技能资源并更新攻击预制体

1.  删除废弃的技能图片、动画剪辑和旧的攻击预制体
2.  新增aw1/aw2/aw3/b3新攻击预制体
3.  调整现有攻击预制体的尺寸、缩放和精灵帧引用
4.  更新fb-2动画和预制体的配置

assets/resources/game/skill/atk/a3.prefab

@@ -134,7 +134,7 @@
     "_contentSize": {
       "__type__": "cc.Size",
       "width": 90,
-      "height": 90
+      "height": 96
     },
     "_anchorPoint": {
       "__type__": "cc.Vec2",
@@ -170,7 +170,7 @@
       "a": 255
     },
     "_spriteFrame": {
-      "__uuid__": "2842dc10-d89e-4ff6-8a11-6d09bf48cf20@048d1",
+      "__uuid__": "abc35b6e-b052-4835-a3a3-cb85abd47f4d@cb920",
       "__expectedType__": "cc.SpriteFrame"
     },
     "_type": 0,
@@ -186,7 +186,7 @@
     "_isTrimmedMode": true,
     "_useGrayscale": false,
     "_atlas": {
-      "__uuid__": "2842dc10-d89e-4ff6-8a11-6d09bf48cf20",
+      "__uuid__": "abc35b6e-b052-4835-a3a3-cb85abd47f4d",
       "__expectedType__": "cc.SpriteAtlas"
     },
     "_id": ""