feat(hero): add hero upgrade function

1. 新增英雄升级相关UI控件与事件流程
2. 实现升级消耗计算与统一扣费逻辑
3. 添加升级预览确认弹窗与属性成长展示
4. 开放tryUpgradeHeroByEid与applyHeroLevel为公共方法

assets/script/game/common/config/GameEvent.ts

@@ -68,6 +68,8 @@ export enum GameEvent {
     MonDead = "MonDead",
     HeroDead = "HeroDead",
     HeroSell = "HeroSell",
+    /** 英雄面板升级按钮点击事件（payload: { eid }，由 MissionCardComp 执行升级） */
+    HeroUpgrade = "HeroUpgrade",
     GOLD_UPDATE = "GOLD_UPDATE",
     DIAMOND_UPDATE = "DIAMOND_UPDATE",
     MEAT_UPDATE = "MEAT_UPDATE",