feat: 人生事件和剧本收藏从 localStorage 切换为真实 API

- 后端：新增 t_event_favorite 表（UNIQUE KEY + MyBatis-Plus Entity）
- 后端：LifeEventController 新增 /favorite/toggle、/favorite/page、/favorite/check 三个真实端点
- 后端：EventFavoriteService 完整 CRUD，含 toggle/分页/批量查询/状态检查
- 后端：删除旧的 favorite-placeholder mock 端点
- 前端：life-event/detail.vue 从 localStorage 假收藏切换为真实 API + localStorage 缓存防闪烁
- 前端：ScriptLibraryView.vue 从 localFavorites 切换为 checkFavoriteScript 真实 API
- 前端：stores/app.js 新增 toggleEventFavorite / checkEventFavorite 方法
- 修复：审核发现的 UNIQUE 约束缺失、未使用 watch 导入、Controller 参数注解遗漏、Controller 委托 Service 构造 Response

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mini-program/src/stores/app.js

@@ -232,10 +232,19 @@ const shareEvent = async (eventData) => {
   }
 }
 
-const favoriteEvent = async ({ id, favorite }) => {
+const toggleEventFavorite = async (eventId) => {
   try {
-    const res = await lifeEventService.favoriteEvent({ id, favorite })
-    return { success: true, data: res.data }
+    const result = await lifeEventService.toggleFavoriteEvent(eventId)
+    return { success: true, data: result }
+  } catch (error) {
+    return { success: false, error: error.message }
+  }
+}
+
+const checkEventFavorite = async (eventId) => {
+  try {
+    const isFavorited = await lifeEventService.checkFavoriteEvent(eventId)
+    return { success: true, data: isFavorited }
   } catch (error) {
     return { success: false, error: error.message }
   }
@@ -479,7 +488,8 @@ export const useAppStore = () => {
     assistEventWriting,
     chatAboutEvent,
     shareEvent,
-    favoriteEvent,
+    toggleEventFavorite,
+    checkEventFavorite,
     getEventById,
     fetchScripts,
     createScript,