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/Include/DecalInputImpl.h

@@ -0,0 +1,68 @@
+// DecalInputImpl.h
+// Declaration of classes for inputing Input Actions
+
+#ifndef __DECALINPUTIMPL_H
+#define __DECALINPUTIMPL_H
+
+#include "DecalInput.h"
+
+template< class ImplT >
+class IInputActionImpl
+: public IInputAction
+{
+public:
+   CComPtr< IInputActionSite > m_pSite;
+
+   HRESULT onLoad( LPTSTR szData )
+   {
+      return S_OK;
+   }
+
+   STDMETHOD(Initialize)(IInputActionSite *pSite, BSTR strData)
+   {
+      USES_CONVERSION;
+
+      m_pSite = pSite;
+      HRESULT hRes = static_cast< ImplT * >( this )->onLoad( OLE2T( strData ) );
+      if( FAILED( hRes ) )
+         m_pSite.Release();
+
+      return hRes;
+   }
+
+   STDMETHOD(Terminate)()
+   {
+      m_pSite.Release();
+
+      return S_OK;
+   }
+
+   // Default Implementation returns false
+   STDMETHOD(get_Stackable)(VARIANT_BOOL *pVal)
+   {
+      *pVal = VARIANT_FALSE;
+      return S_OK;
+   }
+
+   STDMETHOD(Push)()
+   {
+      return S_OK;
+   }
+
+   STDMETHOD(Pop)()
+   {
+      return S_OK;
+   }
+
+   STDMETHOD(Execute)()
+   {
+      return S_OK;
+   }
+
+   STDMETHOD(Reset)()
+   {
+      return S_OK;
+   }
+};
+
+#endif