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/Services/TempFileManager.cs

@@ -0,0 +1,74 @@
+using System.IO;
+using Microsoft.Extensions.Logging;
+
+namespace EnvelopeGenerator.WorkerService.Services;
+
+public sealed class TempFileManager
+{
+    private readonly ILogger<TempFileManager> _logger;
+
+    public TempFileManager(ILogger<TempFileManager> logger)
+    {
+        _logger = logger;
+        TempPath = Path.Combine(Path.GetTempPath(), "EnvelopeGenerator");
+    }
+
+    public string TempPath { get; }
+
+    public Task CreateAsync(CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            if (!Directory.Exists(TempPath))
+            {
+                Directory.CreateDirectory(TempPath);
+                _logger.LogDebug("Created temp folder {TempPath}", TempPath);
+            }
+            else
+            {
+                CleanUpFiles();
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to create temp folder {TempPath}", TempPath);
+            throw;
+        }
+
+        return Task.CompletedTask;
+    }
+
+    public Task CleanupAsync(CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            if (Directory.Exists(TempPath))
+            {
+                _logger.LogDebug("Deleting temp folder {TempPath}", TempPath);
+                Directory.Delete(TempPath, recursive: true);
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to clean up temp folder {TempPath}", TempPath);
+        }
+
+        return Task.CompletedTask;
+    }
+
+    private void CleanUpFiles()
+    {
+        foreach (var file in Directory.GetFiles(TempPath))
+        {
+            try
+            {
+                _logger.LogDebug("Deleting temp file {File}", file);
+                File.Delete(file);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "Failed to delete temp file {File}", file);
+            }
+        }
+    }
+}