feat(assets): 添加新英雄资源并调整动画参数

- 新增 hm6、hm7、hm8、hm9 英雄的目录结构、动画资源和预制体
- 为所有英雄统一调整缩放比例至更合理的数值
- 优化多个英雄的攻击、死亡和最大技能动画的帧率和时长
- 调整 shielded 护盾效果的缩放比例
- 修复部分动画名称错误（如 atk2 改为 dead）
- 新增英雄 0 的预制体资源

assets/resources/game/heros/hero/hm8/atk0.anim

@@ -0,0 +1,71 @@
+[
+  {
+    "__type__": "cc.AnimationClip",
+    "_name": "atk",
+    "_objFlags": 0,
+    "__editorExtras__": {
+      "embeddedPlayerGroups": []
+    },
+    "_native": "",
+    "sample": 15,
+    "speed": 1,
+    "wrapMode": 1,
+    "enableTrsBlending": false,
+    "_duration": 0,
+    "_hash": 500763545,
+    "_tracks": [
+      {
+        "__id__": 1
+      }
+    ],
+    "_exoticAnimation": null,
+    "_events": [],
+    "_embeddedPlayers": [],
+    "_additiveSettings": {
+      "__id__": 6
+    },
+    "_auxiliaryCurveEntries": []
+  },
+  {
+    "__type__": "cc.animation.ObjectTrack",
+    "_binding": {
+      "__type__": "cc.animation.TrackBinding",
+      "path": {
+        "__id__": 2
+      },
+      "proxy": null
+    },
+    "_channel": {
+      "__id__": 4
+    }
+  },
+  {
+    "__type__": "cc.animation.TrackPath",
+    "_paths": [
+      {
+        "__id__": 3
+      },
+      "spriteFrame"
+    ]
+  },
+  {
+    "__type__": "cc.animation.ComponentPath",
+    "component": "cc.Sprite"
+  },
+  {
+    "__type__": "cc.animation.Channel",
+    "_curve": {
+      "__id__": 5
+    }
+  },
+  {
+    "__type__": "cc.ObjectCurve",
+    "_times": [],
+    "_values": []
+  },
+  {
+    "__type__": "cc.AnimationClipAdditiveSettings",
+    "enabled": false,
+    "refClip": null
+  }
+]