移除无用的价格Clamp检测，仅保留8位小数截断

AssetManager.Infrastructure/Services/MarketDataService.cs

@@ -342,14 +342,14 @@ public class MarketDataService : IMarketDataService
             source = "Tiingo";
         }
 
-        // 写入缓存，保留8位小数，强制转换为12位整数+8位小数，避免MySql字段溢出
+        // 写入缓存，保留8位小数
         var cacheEntity = new MarketPriceCache
         {
             Id = cacheKey,
             Symbol = symbol.ToUpper(),
             AssetType = assetType.ToUpper(),
-            Price = Math.Round(Math.Clamp(response.Price, 0, 999999999999.99999999m), 8),
-            PreviousClose = response.PreviousClose > 0 ? Math.Round(Math.Clamp(response.PreviousClose.Value, 0, 999999999999.99999999m), 8) : null,
+            Price = Math.Round(response.Price, 8),
+            PreviousClose = response.PreviousClose > 0 ? Math.Round(response.PreviousClose.Value, 8) : null,
             Source = source,
             FetchedAt = DateTime.Now,
             ExpiredAt = GetCacheExpirationTime(assetType)