Add Rider launch profiles, fix DI and migrations for dev startup

- Rider launch profiles: "ScadaLink Central" and "ScadaLink Site"
- appsettings.Central.json: correct test_infra credentials (ScadaLink_Dev1#,
  scadalink_app user, GLAuth on 3893, Mailpit on 1025)
- Fix HealthMonitoring DI: split site vs central registration to avoid
  missing IHealthReportTransport on central
- Regenerate single clean EF migration (InitialSchema) covering all entities
- Suppress PendingModelChangesWarning in dev mode
- Fix isDevelopment check for ASPNETCORE_ENVIRONMENT propagation

Verified: Host starts, connects to SQL Server, applies migrations, boots
Akka.NET cluster, LDAP auth works (admin/password via GLAuth), health
endpoint returns Healthy.

src/ScadaLink.HealthMonitoring/ServiceCollectionExtensions.cs

@@ -5,12 +5,23 @@ namespace ScadaLink.HealthMonitoring;
 public static class ServiceCollectionExtensions
 {
     /// <summary>
-    /// Register site-side health monitoring services.
+    /// Register site-side health monitoring services (metric collection + periodic reporting).
+    /// Call this on site nodes only. For central, call AddCentralHealthAggregation() instead.
+    /// </summary>
+    public static IServiceCollection AddSiteHealthMonitoring(this IServiceCollection services)
+    {
+        services.AddSingleton<ISiteHealthCollector, SiteHealthCollector>();
+        services.AddHostedService<HealthReportSender>();
+        return services;
+    }
+
+    /// <summary>
+    /// Register shared health monitoring services (safe for both central and site).
+    /// Does not start the HealthReportSender — call AddSiteHealthMonitoring() on site nodes for that.
     /// </summary>
     public static IServiceCollection AddHealthMonitoring(this IServiceCollection services)
     {
         services.AddSingleton<ISiteHealthCollector, SiteHealthCollector>();
-        services.AddHostedService<HealthReportSender>();
         return services;
     }