feat: wire site-local repos, remove config DB from Site, update artifact service

- SiteExternalSystemRepository and SiteNotificationRepository registered in Site DI
- Removed AddConfigurationDatabase from Site role in Program.cs
- Removed ConfigurationDb from appsettings.Site.json
- ArtifactDeploymentService collects all 6 artifact types including data connections and SMTP

src/ScadaLink.SiteRuntime/ServiceCollectionExtensions.cs

@@ -1,6 +1,8 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
+using ScadaLink.Commons.Interfaces.Repositories;
 using ScadaLink.SiteRuntime.Persistence;
+using ScadaLink.SiteRuntime.Repositories;
 using ScadaLink.SiteRuntime.Scripts;
 
 namespace ScadaLink.SiteRuntime;
@@ -38,6 +40,10 @@ public static class ServiceCollectionExtensions
         // WP-17: Shared script library
         services.AddSingleton<SharedScriptLibrary>();
 
+        // Site-local repository implementations backed by SQLite
+        services.AddScoped<IExternalSystemRepository, SiteExternalSystemRepository>();
+        services.AddScoped<INotificationRepository, SiteNotificationRepository>();
+
         return services;
     }