Optimize query with eager loading for related entities

Added `Include` statements to the LINQ query in the
`ReadEnvelopeQueryHandler` class to eagerly load related
entities (`Type`, `EnvelopeReceivers` with `Receiver`, and
`Histories`). This change reduces lazy-loading overhead and
ensures all necessary data is retrieved in a single query,
improving performance.

EnvelopeGenerator.Application/Envelopes/Queries/ReadEnvelopeQuery.cs

@@ -149,6 +149,7 @@ public class ReadEnvelopeQueryHandler : IRequestHandler<ReadEnvelopeQuery, IEnum
             query = query.Where(e => Status.Completed.Contains(e.Status));
 
         var envelopes = await query
+            .Include(e => e.Type)
             .Include(e => e.EnvelopeReceivers).ThenInclude(er => er.Receiver)
             .Include(e => e.Histories)
             .ToListAsync(cancel);