Update AuthController and Login model for API changes

- Updated API documentation in AuthController.cs to include an optional "id" field in the authentication request body.
- Modified the Login record in Login.cs to require a "Password" field and include optional "Id" and "Username" fields, along with updated documentation comments.

EnvelopeGenerator.GeneratorAPI/Models/Login.cs

@@ -3,13 +3,11 @@
 namespace EnvelopeGenerator.GeneratorAPI.Models;
 
 /// <summary>
-/// Anmeldedatenmodell
+/// Repräsentiert ein Login-Modell mit erforderlichem Passwort und optionaler ID und Benutzername.
 /// </summary>
-/// <summary lang="en-US">
-/// Login data model 
-/// </summary>
-/// <param name="Username">Active Directory user name</param>
-/// <param name="Password">Active Directory password</param>
-public record Login([Required]string Username, [Required] string Password)
+/// <param name="Password">Das erforderliche Passwort für das Login.</param>
+/// <param name="Id">Die optionale ID des Benutzers.</param>
+/// <param name="Username">Der optionale Benutzername.</param>
+public record Login([Required] string Password, int? Id = null, string? Username = null)
 {
 }