refactor(Program): simplify Quartz job registration and add EnvelopeTaskApiJob

- Replaced manual FinishEnvelopeJob Quartz setup with ScheduleJobDefault extension
- Added scheduling for EnvelopeTaskApiJob
- Updated using directives to include EnvelopeGenerator.Finalizer namespace
- Improved maintainability by removing redundant Quartz configuration logic

EnvelopeGenerator.Finalizer/Extensions.cs

@@ -23,12 +23,12 @@ public static class Extensions
         IConfiguration configuration)
         where TJob : IJob
     {
-        var expression = configuration[$"{nameof(TJob)}:CronExpression"];
+        var expression = configuration[$"{typeof(TJob).Name}:CronExpression"];
         if (string.IsNullOrWhiteSpace(expression))
             throw new InvalidOperationException(
                 "Cron expression for the Worker job is not configured. " +
                 "Please provide a valid cron schedule in the configuration under " +
-                $"'{nameof(TJob)}:CronExpression'.");
+                $"'{typeof(TJob).FullName}:CronExpression'.");
 
         return q.ScheduleJobDefault<TJob>(expression);
     }