feat(leaderboard): 训练完强刷 + 下拉刷新 force

- 云函数 _fetchLatestByOpenid 支持 force 跳过实例缓存重新扫描
- 训练完成设 _lb_force_refresh 标志,下次打开排行榜强刷,新数据立即可见
- 下拉刷新带 force=true,拉取最新数据
- 平时常规打开仍走 5min 缓存 + 客户端乐观缓存,不增加无谓扫描

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

pages/leaderboard/leaderboard.js

@@ -35,16 +35,20 @@ Page({
       const tb = this.getTabBar()
       if (tb) tb.setData({ selected: 2 })
     } catch (e) {}
-    if (this._firstShow) {
-      this._firstShow = false
-      this.fetchRank()
-      return
-    }
-    this.fetchRank()
+    // 训练完设的强刷标志:下次进排行榜跳过云函数缓存,立刻拿到含新记录的数据
+    let force = false
+    try {
+      if (wx.getStorageSync('_lb_force_refresh')) {
+        force = true
+        wx.removeStorageSync('_lb_force_refresh')
+      }
+    } catch (e) {}
+    this._firstShow = false
+    this.fetchRank(undefined, force)
   },
 
   onPullDownRefresh() {
-    this.fetchRank(() => wx.stopPullDownRefresh())
+    this.fetchRank(() => wx.stopPullDownRefresh(), true)
   },
 
   switchPeriod(e) {
@@ -54,7 +58,7 @@ Page({
     this.fetchRank()
   },
 
-  fetchRank(cb) {
+  fetchRank(cb, force) {
     // 序列号:快速切换周期时丢弃旧响应,避免旧 period 的数据覆盖新 period
     this._fetchSeq = (this._fetchSeq || 0) + 1
     const seq = this._fetchSeq
@@ -81,7 +85,8 @@ Page({
       name: 'leaderboard',
       data: {
         period,
-        maxRank: config.leaderboardMaxRank
+        maxRank: config.leaderboardMaxRank,
+        force: !!force
       }
     }).then(res => {
       if (seq !== this._fetchSeq) { if (cb) cb(); return }  // 过期响应,丢弃