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/Job/EnvelopeTaskApiJob.cs

@@ -0,0 +1,24 @@
+using Quartz;
+
+namespace EnvelopeGenerator.Finalizer.Job
+{
+    public class EnvelopeTaskApiJob : IJob
+    {
+        private readonly ILogger<EnvelopeTaskApiJob> _logger;
+
+        public EnvelopeTaskApiJob(ILogger<EnvelopeTaskApiJob> logger)
+        {
+            _logger = logger;
+        }
+
+        public Task Execute(IJobExecutionContext context)
+        {
+            if (_logger.IsEnabled(LogLevel.Information))
+            {
+                _logger.LogInformation("{jobName} running at: {time}", GetType().FullName, DateTimeOffset.Now);
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}