Add kaigen debit credit for backtest

src/Managing.Application.Abstractions/Services/IKaigenService.cs

@@ -0,0 +1,20 @@
+namespace Managing.Application.Abstractions.Services;
+
+public interface IKaigenService
+{
+    /// <summary>
+    /// Debits user credits for a backtest operation
+    /// </summary>
+    /// <param name="userName">The username to debit</param>
+    /// <param name="debitAmount">The amount to debit</param>
+    /// <returns>The request ID for tracking</returns>
+    Task<string> DebitUserCreditsAsync(string userName, decimal debitAmount);
+
+    /// <summary>
+    /// Refunds user credits if debit operation fails
+    /// </summary>
+    /// <param name="requestId">The original request ID from debit operation</param>
+    /// <param name="userName">The username to refund</param>
+    /// <returns>True if refund was successful</returns>
+    Task<bool> RefundUserCreditsAsync(string requestId, string userName);
+}