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/hm789.png.meta

@@ -0,0 +1,42 @@
+{
+  "ver": "1.0.27",
+  "importer": "image",
+  "imported": true,
+  "uuid": "514c3ee3-cc3c-4947-ae47-c29db8105d76",
+  "files": [
+    ".json",
+    ".png"
+  ],
+  "subMetas": {
+    "6c48a": {
+      "importer": "texture",
+      "uuid": "514c3ee3-cc3c-4947-ae47-c29db8105d76@6c48a",
+      "displayName": "hm789",
+      "id": "6c48a",
+      "name": "texture",
+      "userData": {
+        "wrapModeS": "repeat",
+        "wrapModeT": "repeat",
+        "minfilter": "linear",
+        "magfilter": "linear",
+        "mipfilter": "none",
+        "anisotropy": 0,
+        "isUuid": true,
+        "imageUuidOrDatabaseUri": "514c3ee3-cc3c-4947-ae47-c29db8105d76",
+        "visible": false
+      },
+      "ver": "1.0.22",
+      "imported": true,
+      "files": [
+        ".json"
+      ],
+      "subMetas": {}
+    }
+  },
+  "userData": {
+    "type": "texture",
+    "hasAlpha": true,
+    "fixAlphaTransparencyArtifacts": false,
+    "redirect": "514c3ee3-cc3c-4947-ae47-c29db8105d76@6c48a"
+  }
+}