feat StayExport - Refactor Export Services.

- Created new service: IStayExportService" for common export operations.
- Updated older services to be "IStayExportFormatProvider". This services will only implement the export format.
- Renamed "IStayExportServiceFactory" to "IStayExportFormatProviderFactory" as this factory now is used to get the format providers for the given format.

src/Somnia.GuestLog/Services/StayExport/StayExportFormatProviderFactory.cs

@@ -0,0 +1,30 @@
+using Microsoft.Extensions.Options;
+using Somnia.GuestLog.Enums.Models;
+using Somnia.GuestLog.Models.Configuration;
+using Somnia.GuestLog.Utils.DI;
+
+namespace Somnia.GuestLog.Services.StayExport;
+
+public class StayExportFormatProviderFactory(
+    IServiceProvider serviceProvider,
+    IOptions<StayExportConfig> config
+) : IStayExportFormatProviderFactory, IFactoryDI
+{
+    public static void RegisterFactoryItems(IServiceCollection services)
+    {
+        services.AddKeyedSingleton<IStayExportFormatProvider, StayExportProviderJson>(StayExportFormat.GuestLogJson);
+        services.AddKeyedSingleton<IStayExportFormatProvider, StayExportProviderSpainParteViajeros>(StayExportFormat.SpainParteViajeros);
+    }
+
+
+    public IStayExportFormatProvider GetProvider(StayExportFormat exportFormat)
+    {
+        if (config.Value.EnableStayExport == false)
+        {
+            throw new InvalidOperationException("StayExport is disabled. Enable and configure it first!");
+        }
+
+        return serviceProvider.GetKeyedService<IStayExportFormatProvider>(exportFormat)
+            ?? throw new InvalidOperationException($"StayExport service not found for ExportFormat: '{exportFormat}'");
+    }
+}