Adds SlpModularCms.Api.Slave for local master/slave dev testing (Unit 1)

Relocates ModuleOrchestrator, ServiceCollectionExtensions, and
ApiPrefixConvention from SlpModularCms.Api into SlpModularCms.Core.Hosting
so a new Master-less SlpModularCms.Api.Slave host project (ports 5285/7222)
can share the same bootstrap code without duplicating it. This lets a
developer run a master instance and a slave instance side by side locally
to test the master/slave connection, without touching the existing
master/slave protocol itself.

Relocates the two orchestrator/convention test files from
Modules.Identity.Tests to Core.Tests, dropping an incidental
ProjectReference to SlpModularCms.Api that existed only for those tests.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/SlpModularCms.Core/Hosting/ModuleOrchestrator.cs

@@ -0,0 +1,107 @@
+using System.Reflection;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using SlpModularCms.Core.Modules;
+
+namespace SlpModularCms.Core.Hosting;
+
+/// <summary>
+/// Orkestrator die modules ontdekt en hun lifecycle beheert.
+/// </summary>
+public class ModuleOrchestrator
+{
+    private readonly List<IModule> _modules = new();
+    private readonly ILogger<ModuleOrchestrator> _logger;
+
+    public ModuleOrchestrator(ILogger<ModuleOrchestrator> logger)
+    {
+        _logger = logger;
+    }
+
+    public void DiscoverModules()
+    {
+        _logger.LogInformation("Start module discovery...");
+
+        // Forceer het laden van module assemblies van disk
+        var path = AppDomain.CurrentDomain.BaseDirectory;
+        var moduleFiles = Directory.GetFiles(path, "SlpModularCms.Modules.*.dll");
+
+        foreach (var file in moduleFiles)
+        {
+            try
+            {
+                var assemblyName = AssemblyName.GetAssemblyName(file);
+                if (AppDomain.CurrentDomain.GetAssemblies().All(a => a.FullName != assemblyName.FullName))
+                {
+                    Assembly.Load(assemblyName);
+                    _logger.LogDebug("Assembly geladen: {AssemblyName}", assemblyName.Name);
+                }
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "Kon assembly niet laden van disk: {FilePath}", file);
+            }
+        }
+
+        var assemblies = AppDomain.CurrentDomain.GetAssemblies()
+            .Where(a => a.FullName != null && a.FullName.StartsWith("SlpModularCms.Modules"))
+            .ToList();
+
+        foreach (var assembly in assemblies)
+        {
+            var moduleTypes = assembly.GetTypes()
+                .Where(t => typeof(IModule).IsAssignableFrom(t) && !t.IsInterface && !t.IsAbstract);
+
+            foreach (var type in moduleTypes)
+            {
+                try
+                {
+                    if (Activator.CreateInstance(type) is IModule module)
+                    {
+                        _modules.Add(module);
+                        _logger.LogInformation("Module ontdekt: {ModuleName} v{Version}", module.Name, module.Version);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogError(ex, "Fout bij het instantiëren van module type {TypeName}", type.FullName);
+                }
+            }
+        }
+
+        _logger.LogInformation("{Count} modules succesvol geladen.", _modules.Count);
+    }
+
+    public void RegisterModuleServices(IServiceCollection services)
+    {
+        foreach (var module in _modules)
+        {
+            try
+            {
+                module.RegisterServices(services);
+                _logger.LogInformation("Services geregistreerd voor module: {ModuleName}", module.Name);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Fout bij het registreren van services voor module {ModuleName}", module.Name);
+            }
+        }
+    }
+
+    public void UseModules(IApplicationBuilder app)
+    {
+        foreach (var module in _modules)
+        {
+            try
+            {
+                module.UseModule(app);
+                _logger.LogInformation("Module geactiveerd in pipeline: {ModuleName}", module.Name);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Fout bij het activeren van module {ModuleName} in de pipeline", module.Name);
+            }
+        }
+    }
+}