fix: 13项数据存储与排行榜修复

致命修复:
- leaderboard: 日榜日期比较改用 dateOnly() 替代严格全等
- plan: 计划天数计算日期比较改用 dateOnly()
- cloud: pullAll 添加 orderBy('updatedAt','desc') 确保取最新文档避免数据丢失

严重修复:
- cloud: 新增 cancelPendingPush() 防止清除数据后被延迟推送复活
- settings: _doClearData 补充 user_profile 清除, 先取消推送再清除
- app: 云端同步改为时间戳比对策略, 支持跨设备拉取
- app: _restoreFromCloud 增加空数据保护和 profile 恢复
- storage: 记录ID改用时间戳+自增计数器确保唯一性

中等修复:
- cloud: init/_fetchOpenid 日志升级, 新增 syncStatus getter
- leaderboard云函数: 添加90天活跃过滤减少全表扫描
- storage: validateStreak 增加lastDate无记录时的通用修复
- leaderboard页面: 云函数失败时Toast提示用户而非静默降级

轻微修复:
- timer: onUnload 添加 voice.destroy() 释放音频上下文
- records: onLongPressDelete 委托给 onDeleteRecord 消除重复代码

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

app.js

@@ -39,15 +39,40 @@ App({
     if (cloud.enabled) {
       try {
         const cloudData = await cloud.pullAll()
-        if (!records || Object.keys(records).length === 0) {
-          // Case 1: Fresh install (or user cleared local) — restore from cloud
+        const hasLocal = records && Object.keys(records).length > 0
+        const hasCloud = cloudData && cloudData.records
+          && Object.keys(cloudData.records).length > 0
+          && Object.values(cloudData.records).some(arr => Array.isArray(arr) && arr.length > 0)
+
+        // Parse cloud updatedAt into a comparable timestamp
+        let cloudTs = 0
+        if (cloudData && cloudData.updatedAt) {
+          const d = cloudData.updatedAt instanceof Date
+            ? cloudData.updatedAt
+            : new Date(cloudData.updatedAt)
+          cloudTs = d.getTime() || 0
+        }
+        const localSyncAt = wx.getStorageSync('_cloud_sync_at') || 0
+
+        if (!hasLocal && hasCloud) {
+          // Case 1: Fresh install on a new device — restore from cloud
           this._restoreFromCloud(cloudData)
-        } else {
-          // Case 2: Has local data — push to cloud (local is authoritative)
-          // pullAll already populated _openid / _docId, so pushAll will
-          // update the existing doc instead of creating a duplicate.
+          wx.setStorageSync('_cloud_sync_at', cloudTs)
+        } else if (hasLocal && hasCloud) {
+          // Case 2: Both sides have data — compare timestamps
+          if (cloudTs > localSyncAt) {
+            // Cloud is newer (another device synced after our last push)
+            this._restoreFromCloud(cloudData)
+            wx.setStorageSync('_cloud_sync_at', cloudTs)
+          } else {
+            // Local is at least as current — push
+            cloud.pushAll()
+          }
+        } else if (hasLocal && !hasCloud) {
+          // Case 3: Only local data (first-ever sync) — push
           cloud.pushAll()
         }
+        // else: no data anywhere — nothing to sync
       } catch (e) {
         console.error('Cloud sync on launch failed:', e)
       }
@@ -58,7 +83,15 @@ App({
     if (!cloudData) return
     try {
       if (cloudData.records && Object.keys(cloudData.records).length > 0) {
-        wx.setStorageSync('training_records', cloudData.records)
+        // Guard: only restore if at least one month has actual records.
+        // Pre-6d19928 duplicates could leave docs with month keys but
+        // empty arrays, which would wipe local data on restore.
+        const hasAny = Object.values(cloudData.records).some(
+          arr => Array.isArray(arr) && arr.length > 0
+        )
+        if (hasAny) {
+          wx.setStorageSync('training_records', cloudData.records)
+        }
       }
       if (cloudData.settings) {
         wx.setStorageSync('user_settings', cloudData.settings)
@@ -69,6 +102,9 @@ App({
       if (cloudData.customPlans && typeof cloudData.customPlans === 'object') {
         wx.setStorageSync('custom_plans', cloudData.customPlans)
       }
+      if (cloudData.profile && typeof cloudData.profile === 'object') {
+        wx.setStorageSync('user_profile', cloudData.profile)
+      }
       if (cloudData.themeId) {
         themeMod.setTheme(cloudData.themeId)
       }