feat(share): 启用全站系统分享 + 完善分享文案配置

- 各 Page 补齐 onShareAppMessage/onShareTimeline,修复右上角转发/朋友圈按钮灰色
- ui-btn 透传 open-type,完成弹窗接入分享按钮
- config.share 集中维护文案,动态标题用 titleTemplate 占位符
- leaderboard 的 myEntry.rank 缺失时回退静态标题,避免出现"排第 undefined"
- 完成弹窗分享按钮高度对齐 88rpx,与同排按钮等高

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

pages/timer/timer.js

@@ -470,5 +470,28 @@ Page({
   // No-op handler for catchtouchmove. Swallows move events that would
   // otherwise bubble to underlying timer page controls (causing missed
   // taps on the completion modal).
-  onNoop() { /* swallow */ }
+  onNoop() { /* swallow */ },
+
+  /**
+   * 分享给朋友。训练完成弹窗里的分享按钮会走到这里,标题里拼上用户
+   * 刚才撑了多久,转化率更高;右上角"···"菜单也共用同一份文案。
+   */
+  onShareAppMessage() {
+    const elapsed = this.data.completionElapsed || this.data.duration
+    const s = config.share.timer
+    return {
+      title: s.titleTemplate.replace('{elapsed}', elapsed),
+      path: s.path
+    }
+  },
+
+  /**
+   * 分享到朋友圈,同样带上刚完成的时长晒成绩。
+   */
+  onShareTimeline() {
+    const elapsed = this.data.completionElapsed || this.data.duration
+    return {
+      title: config.share.timer.timelineTitleTemplate.replace('{elapsed}', elapsed)
+    }
+  }
 })