fix: 增强批量获取价格日志级别

- LogWarning → LogError（价格获取失败是严重问题）
- 记录具体错误信息
- 记录 AssetType 用于排查数据源选择问题

AssetManager.Services/PortfolioService.cs

@@ -197,12 +197,14 @@ public class PortfolioService : IPortfolioService
             try
             {
                 var pos = allPositions.First(p => p.StockCode == code);
-                var price = await _marketDataService.GetPriceAsync(code, pos.AssetType ?? "Stock");
+                var assetType = pos.AssetType ?? "Stock";
+                _logger.LogDebug("批量获取价格: {Code}, AssetType={AssetType}", code, assetType);
+                var price = await _marketDataService.GetPriceAsync(code, assetType);
                 return (code, price);
             }
             catch (Exception ex)
             {
-                _logger.LogWarning(ex, "批量获取价格失败: {Code}", code);
+                _logger.LogError(ex, "批量获取价格失败: {Code}, 错误详情: {Message}", code, ex.Message);
                 return (code, null);
             }
         }).ToList();