feat(history): enhance ReadHistoryQuery to support Envelope object and UUID

- Replace nullable `OnlyLast` with non-nullable default `true`
- Support filtering by Envelope object (Id or Uuid) in addition to deprecated EnvelopeId
- Throw `BadRequestException` if no valid Envelope reference is provided
- Preserve status filtering and ordering for latest history entries

EnvelopeGenerator.Application/Histories/Queries/ReadHistoryQuery.cs

@@ -51,9 +51,9 @@ public class ReadHistoryQueryHandler : IRequestHandler<ReadHistoryQuery, IEnumer
     {
         var query = _repo.Query;
 
-        if (request.Envelope?.Id is int envId)
+        if (request.Envelope.Id is int envId)
             query = query.Where(e => e.Id == envId);
-        else if (request.Envelope?.Uuid is string uuid)
+        else if (request.Envelope.Uuid is string uuid)
             query = query.Where(e => e.Envelope!.Uuid == uuid);
 #pragma warning disable CS0618 // Type or member is obsolete
         else if (request.EnvelopeId is not null)