sln build fix (again), tests fixes, audit work and doctors work

src/__Libraries/StellaOps.Doctor.Plugins.Database/DependencyInjection/DatabasePluginServiceCollectionExtensions.cs

@@ -0,0 +1,21 @@
+using Microsoft.Extensions.DependencyInjection;
+using StellaOps.Doctor.Plugins;
+
+namespace StellaOps.Doctor.Plugins.Database.DependencyInjection;
+
+/// <summary>
+/// Extension methods for registering the Database plugin.
+/// </summary>
+public static class DatabasePluginServiceCollectionExtensions
+{
+    /// <summary>
+    /// Adds the Database diagnostic plugin to the Doctor service.
+    /// </summary>
+    /// <param name="services">The service collection.</param>
+    /// <returns>The service collection for chaining.</returns>
+    public static IServiceCollection AddDoctorDatabasePlugin(this IServiceCollection services)
+    {
+        services.AddSingleton<IDoctorPlugin, DatabasePlugin>();
+        return services;
+    }
+}