Add signature submission feature and pipeline updates

Introduced a new feature for submitting signatures, including
backend and frontend changes. Added `SignatureSubmitDto` and
`SubmitAsync` in `SignatureService` to handle signature data
submission. Implemented a new `Submit` endpoint in
`SignatureController` to validate and process signature payloads.

Updated pipeline behaviors to include `SaveSignatureBehavior`
and adjusted the execution order. Enhanced query logic in
`EnvelopeReceiverResolutionBehavior` and `SaveSignatureBehavior`
to align with the updated data model.

Refactored `EGDbContext` to improve trigger handling and logging.
Updated `ReceiverSignedPage.razor` to integrate `SignatureService`
and handle submission errors gracefully. Adjusted application
URLs in `launchSettings.json` and added new database triggers
in `appsettings.json`.

EnvelopeGenerator.Application/Common/Dto/Signature.cs

@@ -49,7 +49,7 @@ public sealed record Signature
     public string? Position
     {
         get => _position;
-        init => _position = string.IsNullOrWhiteSpace(value) ? value : null;
+        init => _position = string.IsNullOrWhiteSpace(value) ? null : value;
     }
 
     /// <summary>
@@ -62,4 +62,4 @@ public sealed record Signature
     /// <b>Example:</b> "Berlin" ? rendered as "Berlin, 26.01.2025"
     /// </summary>
     public required string Place { get; init; }
-}
+}