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/pages/notifications/notifications.ts

@@ -1,3 +1,4 @@
+import { api } from '../../utils/api'
 import { getAvatarGradient, formatTime } from '../../utils/format'
 
 Page({
@@ -11,13 +12,13 @@ Page({
 
   async loadNotifications() {
     try {
-      const res = await wx.cloud.callFunction({ name: 'getNotifications', data: {} }) as any
-      const list = (res.result?.data || []).map((n: any) => ({
+      const list = await api.getNotifications()
+      const enriched = (list || []).map((n: any) => ({
         ...n,
         gradient: getAvatarGradient(n.fromId || ''),
         timeText: formatTime(n.createdAt),
       }))
-      this.setData({ list })
+      this.setData({ list: enriched })
     } catch {}
   },
 
@@ -27,7 +28,7 @@ Page({
   },
 
   onReadAll() {
-    wx.cloud.callFunction({ name: 'markAllRead', data: {} }).catch(() => {})
+    api.markAllRead().catch(() => {})
     const list = this.data.list.map((n: any) => ({ ...n, isRead: true }))
     this.setData({ list })
   },