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/res/Attic/DecalSupportLibraries.manifest

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0"> 
+<assemblyIdentity 
+    version="1.0.0.0" 
+    processorArchitecture="X86" 
+    name="Microsoft.Windows.DecalSupportLibraries"
+    type="win32" 
+/> 
+<description>Your app description here</description> 
+<dependency> 
+    <dependentAssembly> 
+        <assemblyIdentity 
+            type="win32" 
+            name="Microsoft.Windows.Common-Controls" 
+            version="6.0.0.0" 
+            processorArchitecture="X86" 
+            publicKeyToken="6595b64144ccf1df" 
+            language="*" 
+        /> 
+    </dependentAssembly> 
+</dependency> 
+</assembly>

Native/DecalSupportLibraries/res/Attic/DecalSupportLibraries.rc2

@@ -0,0 +1,13 @@
+//
+// DecalSupportLibraries.RC2 - resources Microsoft Visual C++ does not edit directly
+//
+
+#ifdef APSTUDIO_INVOKED
+#error this file is not editable by Microsoft Visual C++
+#endif //APSTUDIO_INVOKED
+
+
+/////////////////////////////////////////////////////////////////////////////
+// Add manually edited resources here...
+
+/////////////////////////////////////////////////////////////////////////////