fix: 数据确认面板修复 - 显示实际数值+确认关闭+侧边栏刷新+清理旧数据

- Handler返回value/unit/isAbnormal到metadata
- DataConfirmCard显示实际数值和单位
- 确认按钮关闭卡片+刷新健康概览
- 健康Agent欢迎卡简化为'查看趋势'
- 清空87条旧健康测试数据

backend/src/Health.WebApi/Endpoints/ai_chat_endpoints.cs

@@ -408,8 +408,10 @@ public static class AiChatEndpoints
                 messageType = "data_confirm";
                 if (toolResult is IDictionary<string, object> resultDict)
                 {
-                    if (resultDict.TryGetValue("type", out var type))
-                        metadata["type"] = type.ToString();
+                    if (resultDict.TryGetValue("type", out var type)) metadata["type"] = type.ToString();
+                    if (resultDict.TryGetValue("value", out var val)) metadata["value"] = val.ToString();
+                    if (resultDict.TryGetValue("unit", out var unit)) metadata["unit"] = unit.ToString();
+                    if (resultDict.TryGetValue("isAbnormal", out var abn) && abn is bool b2) metadata["abnormal"] = b2;
                     if (resultDict.TryGetValue("success", out var success) && success is bool b && b)
                         metadata["success"] = true;
                 }