Add envelope creation functionality and SQL integration

- Updated `EnvelopeGenerator.Application.csproj` to include `Microsoft.Data.SqlClient` package.
- Refactored `CreateEnvelopeReceiverCommand` to inherit from `CreateEnvelopeCommand`.
- Enhanced `CreateEnvelopeSQL` with a SQL script for envelope creation.
- Introduced `CreateEnvelopeCommand` to encapsulate envelope creation data.
- Added `CreateEnvelopeCommandHandler` to process commands and interact with the database.
- Created `CreateEnvelopeResponse` class for handling responses from envelope creation.

EnvelopeGenerator.Application/Envelopes/Commands/CreateEnvelopeCommand.cs

@@ -0,0 +1,24 @@
+using MediatR;
+using System.ComponentModel.DataAnnotations;
+using System.Text.Json.Serialization;
+
+namespace EnvelopeGenerator.Application.Envelopes.Commands;
+
+/// <summary>
+/// Befehl zur Erstellung eines Umschlags.
+/// </summary>
+/// <param name="Title">Der Titel des Umschlags. Dies ist ein Pflichtfeld.</param>
+/// <param name="Message">Die Nachricht, die im Umschlag enthalten sein soll. Dies ist ein Pflichtfeld.</param>
+/// <param name="TFAEnabled">Gibt an, ob die Zwei-Faktor-Authentifizierung für den Umschlag aktiviert ist. Standardmäßig false.</param>
+public record CreateEnvelopeCommand(
+    [Required] string Title,
+    [Required] string Message,
+    bool TFAEnabled = false
+    ) : IRequest<CreateEnvelopeResponse?>
+{
+    /// <summary>
+    /// Id of receiver
+    /// </summary>
+    [JsonIgnore]
+    public int? UserId { get; set; }
+};

EnvelopeGenerator.Application/Envelopes/Commands/CreateEnvelopeCommandHandler.cs

@@ -0,0 +1,49 @@
+using AutoMapper;
+using EnvelopeGenerator.Application.Contracts.SQLExecutor;
+using EnvelopeGenerator.Domain.Entities;
+using MediatR;
+using Microsoft.Data.SqlClient;
+
+namespace EnvelopeGenerator.Application.Envelopes.Commands;
+
+/// <summary>
+/// 
+/// </summary>
+public class CreateEnvelopeCommandHandler : IRequestHandler<CreateEnvelopeCommand, CreateEnvelopeResponse?>
+{
+    private readonly ISQLExecutor<Envelope> _sqlExecutor;
+
+    private readonly IMapper _mapper;
+
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="sqlExecutor"></param>
+    /// <param name="mapper"></param>
+    public CreateEnvelopeCommandHandler(ISQLExecutor<Envelope> sqlExecutor, IMapper mapper)
+    {
+        _sqlExecutor = sqlExecutor;
+        _mapper = mapper;
+    }
+
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="request"></param>
+    /// <param name="cancellationToken"></param>
+    /// <returns></returns>
+    public async Task<CreateEnvelopeResponse?> Handle(CreateEnvelopeCommand request, CancellationToken cancellationToken)
+    {
+        object[] parameters = new object[]
+        {
+            new SqlParameter("@UserId", request.UserId),
+            new SqlParameter("@Title", request.Title),
+            new SqlParameter("@TfaEnabled", request.TFAEnabled ? 1 : 0),
+            new SqlParameter("@Message", request.Message)
+        };
+
+        var envelope = await _sqlExecutor.Execute<CreateEnvelopeSQL>(cancellationToken, parameters).FirstOrDefaultAsync();
+
+        return _mapper.Map<CreateEnvelopeResponse>(envelope);
+    }
+}

EnvelopeGenerator.Application/Envelopes/Commands/CreateEnvelopeResponse.cs

@@ -0,0 +1,8 @@
+namespace EnvelopeGenerator.Application.Envelopes.Commands;
+
+/// <summary>
+/// 
+/// </summary>
+public class CreateEnvelopeResponse
+{
+}

EnvelopeGenerator.Application/Envelopes/Commands/CreateEnvelopeSQL.cs

@@ -1,5 +1,6 @@
 using EnvelopeGenerator.Application.Contracts.SQLExecutor;
 using EnvelopeGenerator.Domain.Entities;
+using Microsoft.Data.SqlClient;
 
 namespace EnvelopeGenerator.Application.Envelopes.Commands;
 /// <summary>
@@ -10,5 +11,19 @@ public class CreateEnvelopeSQL : ISQL<Envelope>
     /// <summary>
     /// 
     /// </summary>
-    public string Raw => string.Empty;
+    public string Raw => @"
+        USE [DD_ECM];
+        DECLARE @OUT_UID varchar(36);
+
+        EXEC [dbo].[PRSIG_API_CREATE_ENVELOPE]
+            @USER_ID = @UserId,
+            @TITLE = @Title,
+            @TFAEnabled = @TfaEnabled,
+            @MESSAGE = @Message,
+            @OUT_UID = @OUT_UID OUTPUT;
+
+        SELECT *
+        FROM [dbo].[TBSIG_ENVELOPE]
+        WHERE [ENVELOPE_UUID] = @OUT_UID;
+    ";
 }