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>

Native/Inject/InjectService.h

@@ -0,0 +1,52 @@
+// InjectService.h : Declaration of the cInjectService
+
+#ifndef __INJECTSERVICE_H_
+#define __INJECTSERVICE_H_
+
+#include "resource.h"       // main symbols
+#include <DecalImpl.h>
+
+/////////////////////////////////////////////////////////////////////////////
+// cInjectService
+class ATL_NO_VTABLE cInjectService : 
+	public CComObjectRootEx<CComSingleThreadModel>,
+	public CComCoClass<cInjectService, &CLSID_InjectService>,
+	public IInjectService,
+   public IDecalServiceImpl<cInjectService>,
+   public IDecalDirectory
+{
+public:
+	cInjectService()
+	{
+	}
+
+DECLARE_REGISTRY_RESOURCEID(IDR_INJECTSERVICE)
+
+DECLARE_PROTECT_FINAL_CONSTRUCT()
+
+BEGIN_COM_MAP(cInjectService)
+	COM_INTERFACE_ENTRY(IInjectService)
+   COM_INTERFACE_ENTRY(IDecalService)
+   COM_INTERFACE_ENTRY(IDecalDirectory)
+END_COM_MAP()
+
+// IDecalService
+   STDMETHOD(BeforePlugins)();
+   STDMETHOD(AfterPlugins)();
+
+// IDecalDirectory
+   STDMETHOD(Lookup)(BSTR strName, IUnknown **ppvItf)
+   {
+      if ( ::wcsicmp ( strName, L"site" ) != 0 )
+         return E_INVALIDARG;
+
+      return get_Site ( reinterpret_cast< IPluginSite ** > ( ppvItf ) );
+   }
+
+// IInjectService
+public:
+	STDMETHOD(InitPlugin)(IUnknown *pUnk);
+	STDMETHOD(get_Site)(/*[out, retval]*/ IPluginSite **pVal);
+};
+
+#endif //__INJECTSERVICE_H_