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/chat/chat.ts

@@ -18,6 +18,7 @@ Page({
   onLoad(query: { userId?: string }) {
     const info = wx.getSystemInfoSync()
     this.setData({ statusBarHeight: info.statusBarHeight, peerId: query.userId || '' })
+    this.loadPeerInfo()
     this.loadMessages()
     this.subscribeRealtime()
   },
@@ -26,9 +27,18 @@ Page({
     this._watcher?.close()
   },
 
-  async loadMessages() {
+  async loadPeerInfo() {
+    if (!this.data.peerId) return
     try {
-      const res = await api.getMessages()
+      const user = await api.getUserProfile(this.data.peerId)
+      this.setData({ peerName: user.nickName || '宠物爱好者' })
+    } catch {}
+  },
+
+  async loadMessages() {
+    if (!this.data.peerId) return
+    try {
+      const res = await api.getMessages(this.data.peerId)
       const msgs = res.list.map((m: any) => ({
         ...m,
         isMe: m.fromId === app.globalData?.userInfo?._id,