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/DecalInput/InputBuffer.rgs

@@ -0,0 +1,26 @@
+HKCR
+{
+	DecalInput.InputBuffer.1 = s 'InputBuffer Class'
+	{
+		CLSID = s '{F0A17A04-7F8F-4A17-A41D-8C297A1E929B}'
+	}
+	DecalInput.InputBuffer = s 'InputBuffer Class'
+	{
+		CLSID = s '{F0A17A04-7F8F-4A17-A41D-8C297A1E929B}'
+		CurVer = s 'DecalInput.InputBuffer.1'
+	}
+	NoRemove CLSID
+	{
+		ForceRemove {F0A17A04-7F8F-4A17-A41D-8C297A1E929B} = s 'InputBuffer Class'
+		{
+			ProgID = s 'DecalInput.InputBuffer.1'
+			VersionIndependentProgID = s 'DecalInput.InputBuffer'
+			ForceRemove 'Programmable'
+			InprocServer32 = s '%MODULE%'
+			{
+				val ThreadingModel = s 'Apartment'
+			}
+			'TypeLib' = s '{3A985F2B-BAD5-43BF-9008-ED4EBBB45B6E}'
+		}
+	}
+}