feat: 新增技能图标英雄语境覆写功能

1. 扩展SkillOverrides接口，新增icon字段支持自定义图标
2. 前端常量与编辑器适配：新增字符串型覆写类型与图标候选选择器
3. 新增getHeroSkillIcon工具函数，实现英雄专属图标优先级加载逻辑
4. 修复并优化技能图标展示逻辑，支持同底座技能不同英雄差异化图标
5. 重构部分英雄配置格式，统一代码风格

put/web/src/components/OverrideEditor.vue

@@ -1,10 +1,23 @@
 <template>
   <div class="override-editor">
     <div v-for="(item, idx) in rows" :key="idx" class="override-row">
-      <el-select v-model="item.key" placeholder="字段" size="small" style="width: 200px" filterable>
+      <el-select v-model="item.key" placeholder="字段" size="small" style="width: 220px" filterable>
         <el-option v-for="k in availableKeys(idx)" :key="k.key" :label="k.label" :value="k.key" />
       </el-select>
-      <el-input-number v-model="item.value" size="small" :controls="false" style="width: 120px" />
+      <!-- 字符串型覆写（icon）：输入帧名，提供常用候选可筛选 -->
+      <el-select
+        v-if="isStringKey(item.key)"
+        v-model="item.value"
+        placeholder="图标帧名"
+        size="small"
+        style="width: 280px"
+        filterable
+        allow-create
+        default-first-option
+      >
+        <el-option v-for="opt in SKILL_ICON_OPTIONS" :key="opt" :label="opt" :value="opt" />
+      </el-select>
+      <el-input-number v-else v-model="item.value" size="small" :controls="false" style="width: 120px" />
       <el-button type="danger" size="small" text @click="remove(idx)">删除</el-button>
     </div>
     <el-button size="small" @click="add">+ 添加覆盖</el-button>
@@ -13,7 +26,7 @@
 
 <script setup>
 import { ref, watch } from 'vue'
-import { OVERRIDE_KEYS } from '../constants'
+import { OVERRIDE_KEYS, SKILL_ICON_OPTIONS } from '../constants'
 
 const props = defineProps({ modelValue: { type: Object, default: () => ({}) } })
 const emit = defineEmits(['update:modelValue'])
@@ -43,6 +56,11 @@ function availableKeys(idx) {
   return OVERRIDE_KEYS.filter((k) => !used.has(k.key))
 }
 
+// 该覆写字段是否为字符串型（icon 取帧名，非数值）
+function isStringKey(key) {
+  return OVERRIDE_KEYS.find((k) => k.key === key)?.type === 'string'
+}
+
 function add() {
   rows.value.push({ key: '', value: 0 })
 }