fix: 历史数据接口和示例保持一致（移除 resampleFreq）

AssetManager.Infrastructure/Services/MarketDataService.cs

@@ -118,10 +118,9 @@ public class MarketDataService : IMarketDataService
 
             var endDate = DateTime.UtcNow;
             var startDate = CalculateStartDate(endDate, timeframe, limit);
-            var resampleFreq = GetTiingoResampleFreq(timeframe);
 
-            // Tiingo 历史数据端点
+            // Tiingo 历史数据端点（和示例一致）
-            var url = $"https://api.tiingo.com/tiingo/daily/{symbol}/prices?startDate={startDate:yyyy-MM-dd}&endDate={endDate:yyyy-MM-dd}&resampleFreq={resampleFreq}&token={_tiingoApiKey}";
+            var url = $"https://api.tiingo.com/tiingo/daily/{symbol}/prices?startDate={startDate:yyyy-MM-dd}&endDate={endDate:yyyy-MM-dd}&token={_tiingoApiKey}";
             var response = await _httpClient.GetFromJsonAsync<List<TiingoDailyResponse>>(url);
 
             if (response == null)
@@ -209,24 +208,6 @@ public class MarketDataService : IMarketDataService
         }
     }
 
-    /// <summary>
-    /// 转换为 Tiingo 的 resampleFreq
-    /// </summary>
-    private string GetTiingoResampleFreq(string timeframe)
-    {
-        return timeframe.ToLower() switch
-        {
-            "1min" => "1min",
-            "5min" => "5min",
-            "15min" => "15min",
-            "1h" => "1hour",
-            "1d" => "daily",
-            "1w" => "weekly",
-            "1m" => "monthly",
-            _ => "daily"
-        };
-    }
-
     /// <summary>
     /// 计算开始日期
     /// </summary>