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/utils/constants.ts

@@ -1,28 +1,5 @@
 export const CLOUD_ENV = 'cloud1-d4g697lte499543d8'
 
-export const COLORS = {
-  pink: '#ff4f91',
-  orange: '#ff9f1c',
-  yellow: '#ffe15a',
-  green: '#2fd37a',
-  mint: '#67e8c9',
-  blue: '#4d8dff',
-  violet: '#8c5cff',
-  ink: '#272235',
-  bgPrimary: '#fff9fb',
-  textPrimary: '#272235',
-  textSecondary: '#6a6178',
-  textTertiary: '#9b8fa8',
-}
-
-export const AVATAR_GRADIENTS = [
-  'linear-gradient(135deg, #ffd6e8, #fff1a6)',
-  'linear-gradient(135deg, #ffe7a0, #b7f4d2)',
-  'linear-gradient(135deg, #c9f7df, #d9d2ff)',
-  'linear-gradient(135deg, #cfe8ff, #ffd6e8)',
-  'linear-gradient(135deg, #e3d8ff, #ffd6e8)',
-]
-
 export const MOOD_OPTIONS = [
   { label: '开心 😄', value: 'happy' },
   { label: '累了 😮‍💨', value: 'tired' },