feat(skill): 新增多种攻击技能动画与配置

新增冰、火、水等元素的攻击技能动画（.anim）与预制体（.prefab），包括冰球、火球、水球、火墙及不同颜色的箭矢。同时更新技能配置表（SkillSet.ts），将原有技能ID 6002-6004重新命名为更具描述性的名称，并新增技能ID 6005-6008以对应新的技能资源。删除了旧版技能资源文件（b_arrow_* 和 m_water_ball_1）。

assets/resources/game/skill/anm/atk/fire_wall.anim

@@ -0,0 +1,120 @@
+[
+  {
+    "__type__": "cc.AnimationClip",
+    "_name": "fire_wall",
+    "_objFlags": 0,
+    "__editorExtras__": {
+      "embeddedPlayerGroups": []
+    },
+    "_native": "",
+    "sample": 12,
+    "speed": 1,
+    "wrapMode": 2,
+    "enableTrsBlending": false,
+    "_duration": 0.6666666666666666,
+    "_hash": 500763545,
+    "_tracks": [
+      {
+        "__id__": 1
+      }
+    ],
+    "_exoticAnimation": null,
+    "_events": [],
+    "_embeddedPlayers": [],
+    "_additiveSettings": {
+      "__id__": 7
+    },
+    "_auxiliaryCurveEntries": []
+  },
+  {
+    "__type__": "cc.animation.ObjectTrack",
+    "_binding": {
+      "__type__": "cc.animation.TrackBinding",
+      "path": {
+        "__id__": 2
+      },
+      "proxy": null
+    },
+    "_channel": {
+      "__id__": 5
+    }
+  },
+  {
+    "__type__": "cc.animation.TrackPath",
+    "_paths": [
+      {
+        "__id__": 3
+      },
+      {
+        "__id__": 4
+      },
+      "spriteFrame"
+    ]
+  },
+  {
+    "__type__": "cc.animation.HierarchyPath",
+    "path": "Node"
+  },
+  {
+    "__type__": "cc.animation.ComponentPath",
+    "component": "cc.Sprite"
+  },
+  {
+    "__type__": "cc.animation.Channel",
+    "_curve": {
+      "__id__": 6
+    }
+  },
+  {
+    "__type__": "cc.ObjectCurve",
+    "_times": [
+      0,
+      0.08333333333333333,
+      0.16666666666666666,
+      0.25,
+      0.3333333333333333,
+      0.4166666666666667,
+      0.5,
+      0.5833333333333334
+    ],
+    "_values": [
+      {
+        "__uuid__": "2423272e-e63b-4736-b15b-30b40cf98a23@ee31b",
+        "__expectedType__": "cc.SpriteFrame"
+      },
+      {
+        "__uuid__": "2423272e-e63b-4736-b15b-30b40cf98a23@6171c",
+        "__expectedType__": "cc.SpriteFrame"
+      },
+      {
+        "__uuid__": "2423272e-e63b-4736-b15b-30b40cf98a23@0a599",
+        "__expectedType__": "cc.SpriteFrame"
+      },
+      {
+        "__uuid__": "2423272e-e63b-4736-b15b-30b40cf98a23@d9355",
+        "__expectedType__": "cc.SpriteFrame"
+      },
+      {
+        "__uuid__": "2423272e-e63b-4736-b15b-30b40cf98a23@09c9f",
+        "__expectedType__": "cc.SpriteFrame"
+      },
+      {
+        "__uuid__": "2423272e-e63b-4736-b15b-30b40cf98a23@4d16f",
+        "__expectedType__": "cc.SpriteFrame"
+      },
+      {
+        "__uuid__": "2423272e-e63b-4736-b15b-30b40cf98a23@2d6fe",
+        "__expectedType__": "cc.SpriteFrame"
+      },
+      {
+        "__uuid__": "2423272e-e63b-4736-b15b-30b40cf98a23@b7d39",
+        "__expectedType__": "cc.SpriteFrame"
+      }
+    ]
+  },
+  {
+    "__type__": "cc.AnimationClipAdditiveSettings",
+    "enabled": false,
+    "refClip": null
+  }
+]