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/DecalSupportLibraries/Attic/DecalSupportLibraries.idl

@@ -0,0 +1,29 @@
+// DecalSupportLibraries.idl : type library source for DecalSupportLibraries.exe
+
+// This file will be processed by the MIDL compiler to produce the
+// type library (DecalSupportLibraries.tlb).
+
+[ uuid(24241FCB-6DD4-4B97-8C1F-88A23084AFA5), version(1.0) ]
+library DecalSupportLibraries
+{
+	importlib("stdole32.tlb");
+	importlib("stdole2.tlb");
+
+	//  Primary dispatch interface for CDecalSupportLibrariesDoc
+	
+	[ uuid(586E5AC4-7A88-4CFA-B075-2D7F0E70250D) ]
+	dispinterface IDecalSupportLibraries
+	{
+		properties:
+			
+		methods:
+	};
+
+	//  Class information for CDecalSupportLibrariesDoc
+	
+	[ uuid(29FC66D6-DFC1-45D0-87AD-52D44949DCBC) ]
+	coclass DecalSupportLibraries
+	{
+		[default] dispinterface IDecalSupportLibraries;
+	};
+};