feat(host): add Serilog logging with console and file sinks

Configure structured logging following logging_style.md guidelines with
daily rolling log files (30-day retention) and proper shutdown handling.

NEW/src/JdeScoping.Host/JdeScoping.Host.csproj

@@ -14,6 +14,10 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Server" Version="10.0.1" />
     <PackageReference Include="Microsoft.Extensions.Hosting.WindowsServices" Version="10.0.1" />
+    <PackageReference Include="Serilog" Version="4.*" />
+    <PackageReference Include="Serilog.Extensions.Logging" Version="8.*" />
+    <PackageReference Include="Serilog.Sinks.Console" Version="6.*" />
+    <PackageReference Include="Serilog.Sinks.File" Version="6.*" />
   </ItemGroup>
 
   <PropertyGroup>

NEW/src/JdeScoping.Host/Program.cs

@@ -4,30 +4,52 @@ using JdeScoping.DataSync.Options;
 using JdeScoping.ExcelIO.Options;
 using JdeScoping.Database;
 using JdeScoping.Host.Startup;
-using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
+using Serilog;
+using Serilog.Events;
 
+// Configure Serilog with console and daily rolling file
+var logsPath = Path.Combine(AppContext.BaseDirectory, "logs");
+Directory.CreateDirectory(logsPath);
+
+Log.Logger = new LoggerConfiguration()
+    .MinimumLevel.Information()
+    .MinimumLevel.Override("Microsoft", LogEventLevel.Warning)
+    .MinimumLevel.Override("Microsoft.AspNetCore", LogEventLevel.Warning)
+    .Enrich.FromLogContext()
+    .WriteTo.Console(
+        outputTemplate: "{Timestamp:HH:mm:ss} [{Level:u3}] {Message:lj}{NewLine}{Exception}")
+    .WriteTo.File(
+        path: Path.Combine(logsPath, "scoping-.log"),
+        rollingInterval: RollingInterval.Day,
+        retainedFileCountLimit: 30,
+        outputTemplate: "{Timestamp:yyyy-MM-dd HH:mm:ss.fff zzz} [{Level:u3}] {Message:lj}{NewLine}{Exception}")
+    .CreateLogger();
+
+try
+{
     var builder = WebApplication.CreateBuilder(args);
 
     // Windows Service support (no-op on non-Windows)
     builder.Host.UseWindowsService();
 
+    // Replace default logging with Serilog
+    builder.Services.AddLogging(logging =>
+    {
+        logging.ClearProviders();
+        logging.AddSerilog(dispose: true);
+    });
+
     // Run database migrations (skip in Testing environment)
     // Note: IDatabaseMigrator interface enables mocking for integration tests
     if (!builder.Environment.IsEnvironment("Testing"))
     {
-    // Create early logger for startup diagnostics
-    using var loggerFactory = LoggerFactory.Create(b => b
-        .AddConfiguration(builder.Configuration.GetSection("Logging"))
-        .AddConsole());
-    var startupLogger = loggerFactory.CreateLogger("JdeScoping.Host.Startup");
-
         IDatabaseMigrator migrator = new DatabaseMigrator(builder.Configuration);
         var migrationResult = migrator.Migrate();
 
         if (!migrationResult.Successful)
         {
-        startupLogger.LogError(migrationResult.Error, "Database migration failed: {ErrorMessage}", migrationResult.Error?.Message);
+            Log.Error(migrationResult.Error, "Database migration failed: {ErrorMessage}", migrationResult.Error?.Message);
             return 1;
         }
     }
@@ -53,7 +75,7 @@ if (!app.Environment.IsEnvironment("Testing"))
 
         if (!ConfigurationValidationRunner.ValidateConfiguration(app.Services, configLogger))
         {
-        configLogger.LogCritical("Application startup aborted due to configuration validation failures");
+            Log.Fatal("Application startup aborted due to configuration validation failures");
             return 1;
         }
     }
@@ -77,9 +99,22 @@ app.UseWebApi();
     app.MapRazorPages();
     app.MapFallbackToFile("index.html");
 
+    // Register shutdown handler for clean Serilog disposal
+    app.Lifetime.ApplicationStopping.Register(Log.CloseAndFlush);
+
     app.Run();
 
     return 0;
+}
+catch (Exception ex)
+{
+    Log.Fatal(ex, "Application terminated unexpectedly");
+    return 1;
+}
+finally
+{
+    Log.CloseAndFlush();
+}
 
 // Validates that critical services are properly registered
 static void ValidateServices(IServiceProvider services)