API NEW CONTROLLER UPDATED - Use light query for EnvelopeReceiver loading

Replaced _mediator.ReadEnvelopeReceiverAsync with a light query (ReadEnvelopeReceiverLightQuery) that excludes Documents and Elements, improving performance by fetching only essential data.

EnvelopeGenerator.API/Controllers/ReceiverAuthController.cs

@@ -89,8 +89,9 @@ public class ReceiverAuthController : ControllerBase
                 });
             }
 
-            // ── EnvelopeReceiver laden ──
-            var er = await _mediator.ReadEnvelopeReceiverAsync(key, cancel);
+            // ── EnvelopeReceiver laden (Light-Query: ohne Documents/Elements) ──
+            var er = await _mediator.Send(
+                new ReadEnvelopeReceiverLightQuery { Key = key }, cancel);
             if (er is null)
                 return NotFound(new ReceiverAuthResponse { Status = "not_found" });