make GetCompletionById return answers included (btw maybe it's not necessary)

SurveyLib.Infrastructure.EFCore/Repositories/CompletionRepository.cs

@@ -16,7 +16,7 @@ public class CompletionRepository : ICompletionRepository
 
     public async Task<Completion?> GetByIdAsync(int id)
     {
-        return await _context.Completions.FindAsync(id);
+        return await _context.Completions.Include(c => c.Answers).FirstOrDefaultAsync(c => c.Id == id);
     }
 
     public async Task<IEnumerable<Completion>> GetAllAsync()