Refactor folder structure for result classes.

Moved InvalidModelStateResult.cs and ServiceResult.cs to the Results folder to better organize result-related classes. This change aims to improve maintainability and clarity of the directory structure.

Author: imclint21

src/Initium/InvalidModelStateResult.cs …itium/Results/InvalidModelStateResult.cssrc/Initium/InvalidModelStateResult.cs renamed to src/Initium/Results/InvalidModelStateResult.cs src/Initium/InvalidModelStateResult.cs renamed to src/Initium/Results/InvalidModelStateResult.cs

@@ -1,7 +1,7 @@
 using Initium.Response;
 using Microsoft.AspNetCore.Mvc;
 
-namespace Initium;
+namespace Initium.Results;
 
 /// <summary>
 /// Represents a custom result for invalid model state, returned as a JSON response with standardized API response structure.

src/Initium/ServiceResult.cs src/Initium/Results/ServiceResult.cssrc/Initium/ServiceResult.cs renamed to src/Initium/Results/ServiceResult.cs

@@ -1,10 +1,10 @@
 using System.Net;
 using System.Text.Json.Serialization;
-using Microsoft.AspNetCore.Mvc;
 using Initium.Exceptions;
 using Initium.Infrastructure;
+using Microsoft.AspNetCore.Mvc;
 
-namespace Initium;
+namespace Initium.Results;
 
 /// <summary>
 /// Represents a result for a service operation, indicating success or failure with an optional message and status code.