Phase 0 WP-0.10–0.12: Host skeleton, options classes, sample configs, and execution framework

- WP-0.10: Role-based Host startup (Central=WebApplication, Site=generic Host),
  15 component AddXxx() extension methods, MapCentralUI/MapInboundAPI stubs
- WP-0.11: 12 per-component options classes with config binding
- WP-0.12: Sample appsettings for central and site topologies
- Add execution procedure and checklist template to generate_plans.md
- Add phase-0-checklist.md for execution tracking
- Resolve all 21 open questions from plan generation
- Update IDataConnection with batch ops and IAsyncDisposable
57 tests pass, zero warnings.

src/ScadaLink.Host/Program.cs

@@ -1,2 +1,106 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+using ScadaLink.CentralUI;
+using ScadaLink.ClusterInfrastructure;
+using ScadaLink.Communication;
+using ScadaLink.ConfigurationDatabase;
+using ScadaLink.DataConnectionLayer;
+using ScadaLink.DeploymentManager;
+using ScadaLink.ExternalSystemGateway;
+using ScadaLink.HealthMonitoring;
+using ScadaLink.Host;
+using ScadaLink.InboundAPI;
+using ScadaLink.NotificationService;
+using ScadaLink.Security;
+using ScadaLink.SiteEventLogging;
+using ScadaLink.SiteRuntime;
+using ScadaLink.StoreAndForward;
+using ScadaLink.TemplateEngine;
+
+var configuration = new ConfigurationBuilder()
+    .AddJsonFile("appsettings.json", optional: false)
+    .AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT") ?? "Production"}.json", optional: true)
+    .AddEnvironmentVariables()
+    .AddCommandLine(args)
+    .Build();
+
+var role = configuration["ScadaLink:Node:Role"]
+    ?? throw new InvalidOperationException("ScadaLink:Node:Role is required");
+
+if (role.Equals("Central", StringComparison.OrdinalIgnoreCase))
+{
+    var builder = WebApplication.CreateBuilder(args);
+    builder.Configuration.AddConfiguration(configuration);
+
+    // Shared components
+    builder.Services.AddClusterInfrastructure();
+    builder.Services.AddCommunication();
+    builder.Services.AddHealthMonitoring();
+    builder.Services.AddExternalSystemGateway();
+    builder.Services.AddNotificationService();
+
+    // Central-only components
+    builder.Services.AddTemplateEngine();
+    builder.Services.AddDeploymentManager();
+    builder.Services.AddSecurity();
+    builder.Services.AddCentralUI();
+    builder.Services.AddInboundAPI();
+    builder.Services.AddConfigurationDatabase();
+
+    // Options binding
+    BindSharedOptions(builder.Services, builder.Configuration);
+    builder.Services.Configure<SecurityOptions>(builder.Configuration.GetSection("ScadaLink:Security"));
+    builder.Services.Configure<InboundApiOptions>(builder.Configuration.GetSection("ScadaLink:InboundApi"));
+
+    var app = builder.Build();
+    app.MapCentralUI();
+    app.MapInboundAPI();
+    await app.RunAsync();
+}
+else if (role.Equals("Site", StringComparison.OrdinalIgnoreCase))
+{
+    var builder = Microsoft.Extensions.Hosting.Host.CreateDefaultBuilder(args);
+    builder.ConfigureAppConfiguration(config => config.AddConfiguration(configuration));
+    builder.ConfigureServices((context, services) =>
+    {
+        // Shared components
+        services.AddClusterInfrastructure();
+        services.AddCommunication();
+        services.AddHealthMonitoring();
+        services.AddExternalSystemGateway();
+        services.AddNotificationService();
+
+        // Site-only components
+        services.AddSiteRuntime();
+        services.AddDataConnectionLayer();
+        services.AddStoreAndForward();
+        services.AddSiteEventLogging();
+
+        // Options binding
+        BindSharedOptions(services, context.Configuration);
+        services.Configure<DataConnectionOptions>(context.Configuration.GetSection("ScadaLink:DataConnection"));
+        services.Configure<StoreAndForwardOptions>(context.Configuration.GetSection("ScadaLink:StoreAndForward"));
+        services.Configure<SiteEventLogOptions>(context.Configuration.GetSection("ScadaLink:SiteEventLog"));
+    });
+
+    var host = builder.Build();
+    await host.RunAsync();
+}
+else
+{
+    throw new InvalidOperationException($"Unknown role: {role}. Must be 'Central' or 'Site'.");
+}
+
+static void BindSharedOptions(IServiceCollection services, IConfiguration config)
+{
+    services.Configure<NodeOptions>(config.GetSection("ScadaLink:Node"));
+    services.Configure<ClusterOptions>(config.GetSection("ScadaLink:Cluster"));
+    services.Configure<DatabaseOptions>(config.GetSection("ScadaLink:Database"));
+    services.Configure<CommunicationOptions>(config.GetSection("ScadaLink:Communication"));
+    services.Configure<HealthMonitoringOptions>(config.GetSection("ScadaLink:HealthMonitoring"));
+    services.Configure<NotificationOptions>(config.GetSection("ScadaLink:Notification"));
+    services.Configure<LoggingOptions>(config.GetSection("ScadaLink:Logging"));
+}
+
+/// <summary>
+/// Exposes the auto-generated Program class for test infrastructure (e.g. WebApplicationFactory).
+/// </summary>
+public partial class Program { }