Enhance query criteria and add partial email matching

- Added `[NotMapped]` attribute to `HasAnyCriteria` in `ReceiverQueryBase` to exclude it from database mapping.
- Made `HasAnyCriteria` in `ReceiverQueryBase` virtual for overriding.
- Introduced `EmailAddressSearch` in `ReadReceiverQuery` for partial email matching.
- Overrode `HasAnyCriteria` in `ReadReceiverQuery` to include `EmailAddressSearch`.
- Updated `ReadReceiverQueryHandler` to support partial email matching using `EF.Functions.Like`.

EnvelopeGenerator.Application/Common/Query/ReceiverQueryBase.cs

@@ -1,4 +1,6 @@
-namespace EnvelopeGenerator.Application.Common.Query;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace EnvelopeGenerator.Application.Common.Query;
 
 /// <summary>
 /// Stellt eine Abfrage dar, um die Details eines Empfängers zu lesen.
@@ -29,5 +31,6 @@ public record ReceiverQueryBase
     /// <see cref="Id"/>, <see cref="EmailAddress"/>, or <see cref="Signature"/> is not null.
     /// <para>Usage example: The query can be executed only if at least one criterion is specified.</para>
     /// </remarks>
-    public bool HasAnyCriteria => Id is not null || EmailAddress is not null || Signature is not null;
+    [NotMapped]
+    public virtual bool HasAnyCriteria => Id is not null || EmailAddress is not null || Signature is not null;
 }