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/Worker.cs

@@ -1,24 +1,71 @@
-namespace EnvelopeGenerator.WorkerService
+using EnvelopeGenerator.WorkerService.Configuration;
+using EnvelopeGenerator.WorkerService.Services;
+using Microsoft.Data.SqlClient;
+using Microsoft.Extensions.Options;
+
+namespace EnvelopeGenerator.WorkerService;
+
+public class Worker : BackgroundService
 {
-    public class Worker : BackgroundService
+    private readonly ILogger<Worker> _logger;
+    private readonly WorkerSettings _settings;
+    private readonly TempFileManager _tempFiles;
+
+    public Worker(
+        ILogger<Worker> logger,
+        IOptions<WorkerSettings> settings,
+        TempFileManager tempFiles)
     {
-        private readonly ILogger<Worker> _logger;
+        _logger = logger;
+        _settings = settings.Value;
+        _tempFiles = tempFiles;
+    }
 
-        public Worker(ILogger<Worker> logger)
+    public override async Task StartAsync(CancellationToken cancellationToken)
+    {
+        _logger.LogInformation("Starting EnvelopeGenerator worker...");
+        _logger.LogInformation("Debug mode: {Debug}", _settings.Debug);
+
+        ValidateConfiguration();
+        await EnsureDatabaseConnectionAsync(cancellationToken);
+        await _tempFiles.CreateAsync(cancellationToken);
+
+        await base.StartAsync(cancellationToken);
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        _logger.LogInformation("EnvelopeGenerator worker is running. Jobs are scheduled every {Interval} minute(s).", Math.Max(1, _settings.IntervalMinutes));
+        await Task.Delay(Timeout.Infinite, stoppingToken);
+    }
+
+    public override async Task StopAsync(CancellationToken cancellationToken)
+    {
+        _logger.LogInformation("Stopping EnvelopeGenerator worker...");
+        await _tempFiles.CleanupAsync(cancellationToken);
+        await base.StopAsync(cancellationToken);
+    }
+
+    private void ValidateConfiguration()
+    {
+        if (string.IsNullOrWhiteSpace(_settings.ConnectionString))
         {
-            _logger = logger;
+            throw new InvalidOperationException("Connection string cannot be empty. Configure 'WorkerSettings:ConnectionString'.");
         }
+    }
 
-        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    private async Task EnsureDatabaseConnectionAsync(CancellationToken cancellationToken)
+    {
+        try
         {
-            while (!stoppingToken.IsCancellationRequested)
-            {
-                if (_logger.IsEnabled(LogLevel.Information))
-                {
-                    _logger.LogInformation("Worker running at: {time}", DateTimeOffset.Now);
-                }
-                await Task.Delay(1000, stoppingToken);
-            }
+            await using var connection = new SqlConnection(_settings.ConnectionString);
+            await connection.OpenAsync(cancellationToken);
+            _logger.LogInformation("Database connection established successfully.");
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Database connection could not be established.");
+            throw;
         }
     }
 }