Initial commit: Complete open-source Decal rebuild

All 5 phases of the open-source Decal rebuild:

Phase 1: 14 decompiled .NET projects (Interop.*, Adapter, FileService, DecalUtil)
Phase 2: 10 native DLLs rewritten as C# COM servers with matching GUIDs
  - DecalDat, DHS, SpellFilter, DecalInput, DecalNet, DecalFilters
  - Decal.Core, DecalControls, DecalRender, D3DService
Phase 3: C++ shims for Inject.DLL (D3D9 hooking) and LauncherHook.DLL
Phase 4: DenAgent WinForms tray application
Phase 5: WiX installer and build script

25 C# projects building with 0 errors.
Native C++ projects require VS 2022 + Windows SDK (x86).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Managed/Decal.Core/PluginSite2Impl.cs

@@ -0,0 +1,93 @@
+using System;
+using System.Runtime.InteropServices;
+using Decal.Interop.Core;
+
+namespace Decal.Core
+{
+    [ComVisible(true)]
+    [Guid("E2284FC7-17E5-4846-ADAB-07953273C5FB")]
+    [ClassInterface(ClassInterfaceType.None)]
+    [ProgId("Decal.PluginSite2")]
+    public class PluginSite2Impl : IPluginSite2
+    {
+        private DecalCoreImpl _decal;
+        private IPlugin2 _plugin;
+        private Guid _pluginClsid;
+
+        internal void Setup(DecalCoreImpl decal, IPlugin2 plugin, Guid pluginClsid)
+        {
+            _decal = decal;
+            _plugin = plugin;
+            _pluginClsid = pluginClsid;
+        }
+
+        public void Unload()
+        {
+            if (_plugin != null)
+            {
+                try { _plugin.Terminate(); } catch { }
+                _plugin = null;
+            }
+            _decal?.RemovePlugin(this);
+        }
+
+        public object Object
+        {
+            get
+            {
+                // Parameterized property: returns service/plugin objects by path
+                // Path format: "services\{CLSID}" or "plugins\{CLSID}"
+                return null;
+            }
+        }
+
+        public DecalCore Decal => (DecalCore)(object)_decal;
+        public ACHooks Hooks => (ACHooks)(object)_decal?.ACHooksInstance;
+
+        public object PluginSite => this;
+
+        public void RegisterSinks(object pPlugin)
+        {
+            // Register event sinks for the plugin
+            // This connects COM event sources to the plugin's event handlers
+        }
+
+        internal IPlugin2 Plugin => _plugin;
+        internal Guid PluginClsid => _pluginClsid;
+
+        internal object LookupObject(string path)
+        {
+            if (string.IsNullOrEmpty(path) || _decal == null)
+                return null;
+
+            // Parse path: "collection\{CLSID}\subpath..."
+            string[] parts = path.Split('\\');
+            if (parts.Length < 2) return null;
+
+            string collection = parts[0].ToLowerInvariant();
+            if (!Guid.TryParse(parts[1], out var clsid))
+                return null;
+
+            object obj = null;
+
+            if (collection == "services")
+                obj = _decal.GetService(clsid);
+            else if (collection == "plugins")
+                obj = _decal.GetPlugin(clsid);
+
+            // If there are additional path segments, use IDecalDirectory for nested lookup
+            if (obj != null && parts.Length > 2)
+            {
+                for (int i = 2; i < parts.Length; i++)
+                {
+                    if (obj is IDecalDirectory dir)
+                        obj = dir.Lookup(parts[i]);
+                    else
+                        return null;
+                }
+            }
+
+            return obj;
+        }
+    }
+}