Refactor: Remove GlobalVar and replace with IAppSettings; restructure affected infrastructure, services, and view models for dependency injection.

Jugenddienst Stunden/Interfaces/IAppSettings.cs

@@ -1,5 +1,10 @@
+using Jugenddienst_Stunden.Types;
+
 namespace Jugenddienst_Stunden.Interfaces;
 
+/// <summary>
+/// Represents the application settings required for configuration and operation of the application.
+/// </summary>
 public interface IAppSettings {
 	string ApiUrl { get; set; }
 	string ApiKey { get; set; }
@@ -7,4 +12,6 @@ public interface IAppSettings {
 	int EmployeeId { get; set; }
 	string Name { get; set; }
 	string Surname { get; set; }
+
+	Settings? Settings { get; set; }
 }