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>

Managed/Decal.Adapter/Decal.Adapter.Messages/AdapterMessageEventArgs.cs

@@ -0,0 +1,68 @@
+using System;
+using System.Collections.Generic;
+
+namespace Decal.Adapter.Messages;
+
+[CLSCompliant(true)]
+public class AdapterMessageEventArgs : EventArgs
+{
+	private EventHandler<AdapterMessageResponseEventArgs> responder;
+
+	private List<object> handlers;
+
+	private bool canAddHandlers;
+
+	internal bool CanAddHandlers
+	{
+		get
+		{
+			return canAddHandlers;
+		}
+		set
+		{
+			canAddHandlers = value;
+		}
+	}
+
+	public event EventHandler<AdapterMessageResponseEventArgs> MessageComplete
+	{
+		add
+		{
+			responder = (EventHandler<AdapterMessageResponseEventArgs>)Delegate.Combine(responder, value);
+		}
+		remove
+		{
+			responder = (EventHandler<AdapterMessageResponseEventArgs>)Delegate.Remove(responder, value);
+		}
+	}
+
+	internal AdapterMessageEventArgs()
+	{
+		handlers = new List<object>();
+	}
+
+	public void AddHandler(object obj)
+	{
+		if (!CanAddHandlers)
+		{
+			throw new InvalidOperationException("Unable to add handlers at this time");
+		}
+		if (obj != null)
+		{
+			handlers.Add(obj);
+		}
+	}
+
+	public void SetComplete(object handler, AdapterMessageResponseEventArgs e)
+	{
+		handlers.Remove(handler);
+		if (handlers.Count == 0)
+		{
+			e.Complete = true;
+		}
+		if (responder != null)
+		{
+			responder(this, e);
+		}
+	}
+}