refactor: 移除战斗结束相关的FEnd触发逻辑

此次提交全面清理了所有与战斗结束（FEnd）相关的代码：
1. 移除了Hero、Monster等实体中的fend属性与运行时处理
2. 删除了SkillTriggerHelper中的FEnd触发分支
3. 移除了GameEvent中的FightEnd事件与相关监听
4. 清理了配置文件中的FEnd相关枚举、字段与装备
5. 重构了MissionComp的回合逻辑，不再触发战后技能
6. 更新了注释与文档，移除过时的FEnd相关说明

彻底移除了已不再使用的战斗结束触发机制，简化了代码架构。

assets/script/game/map/MissionCardComp.ts

@@ -2264,7 +2264,6 @@ export class MissionCardComp extends CCComp {
         model.runtime_call = resolveTriggerByLv(model.call, nextLv);
         model.runtime_dead = resolveTriggerByLv(model.dead, nextLv);
         model.runtime_fstart = resolveTriggerByLv(model.fstart, nextLv);
-        model.runtime_fend = resolveTriggerByLv(model.fend, nextLv);
         model.runtime_atking = resolveTriggerByLv(model.atking, nextLv);
         model.runtime_atked = resolveTriggerByLv(model.atked, nextLv);
         model.runtime_field = resolveFieldByLv(model.field, nextLv);