chore: 清理冗余代码并补全私信/搜索/故事/通知功能

- 删除未使用的空组件目录、死代码导出(clearAuth/calcDistance/COLORS/
  AVATAR_GRADIENTS/Message/TabBarItem/deletePost/uploadImage/getFileURL/
  _initLogin)，确保程序仍可正常运行
- 新增 8 个云函数并补全对应页面逻辑：getMessages/sendMessage(私信聊天)、
  getHotTopics/searchPosts/searchUsers(搜索)、getStory(故事，复用 posts
  集合)、getNotifications/markAllRead(基于点赞评论聚合的通知系统)
- 在 cloudbaserc.json 中注册全部新云函数，并通过 --deployMode zip 完成部署

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

miniprogram/types/index.ts

@@ -71,17 +71,6 @@ export interface Comment {
   createdAt: string
 }
 
-export interface Message {
-  _id: string
-  fromId: string
-  from?: UserProfile
-  toId: string
-  content: string
-  type: 'greeting' | 'text' | 'image'
-  isRead: boolean
-  createdAt: string
-}
-
 export interface NearbyUser {
   userId: string
   user: UserProfile
@@ -93,14 +82,6 @@ export interface NearbyUser {
   location: GeoPoint
 }
 
-export interface TabBarItem {
-  pagePath: string
-  text: string
-  icon: string
-  activeIcon: string
-  selected: boolean
-}
-
 export interface NavBarInfo {
   statusBarHeight: number
   navbarHeight: number