Refactor worker to use config, DI, and Quartz scheduling

- Add WorkerSettings class and update appsettings for config-driven setup
- Integrate Quartz.NET for job scheduling (FinalizeDocumentJob, APIEnvelopeJob)
- Refactor Program.cs for DI of services (TempFileManager, PDFBurner, etc.)
- Implement TempFileManager for temp folder management and cleanup
- Rewrite Worker class for config validation, DB check, and lifecycle logging
- Update csproj to include Quartz and EnvelopeGenerator.Jobs references
- Improve maintainability, error handling, and logging throughout

EnvelopeGenerator.WorkerService/Configuration/WorkerSettings.cs

@@ -0,0 +1,14 @@
+using EnvelopeGenerator.Jobs.FinalizeDocument;
+
+namespace EnvelopeGenerator.WorkerService.Configuration;
+
+public sealed class WorkerSettings
+{
+    public string ConnectionString { get; set; } = string.Empty;
+
+    public bool Debug { get; set; }
+
+    public int IntervalMinutes { get; set; } = 1;
+
+    public PDFBurnerParams PdfBurner { get; set; } = new();
+}