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.DecalNet/WebRequestImpl.cs

@@ -0,0 +1,74 @@
+using System;
+using System.Net;
+using System.Runtime.InteropServices;
+using System.Threading;
+using Decal.Interop.Net;
+
+namespace Decal.DecalNet
+{
+    [ComVisible(true)]
+    [Guid("15631E36-55CB-4D16-ADE7-74D9F8A5F4B6")]
+    [ClassInterface(ClassInterfaceType.None)]
+    [ComSourceInterfaces(typeof(IWebRequestEvents))]
+    [ProgId("DecalNet.WebRequest")]
+    public class WebRequestImpl : IWebRequest
+    {
+        public event IWebRequestEvents_BeginEventHandler Begin;
+        public event IWebRequestEvents_EndEventHandler End;
+
+        public void Get(string strURL)
+        {
+            Begin?.Invoke();
+            ThreadPool.QueueUserWorkItem(_ =>
+            {
+                try
+                {
+                    using (var client = new WebClient())
+                    {
+                        string result = client.DownloadString(strURL);
+                        End?.Invoke(200, result);
+                    }
+                }
+                catch (WebException ex)
+                {
+                    int code = 0;
+                    if (ex.Response is HttpWebResponse resp)
+                        code = (int)resp.StatusCode;
+                    End?.Invoke(code, ex.Message);
+                }
+                catch (Exception ex)
+                {
+                    End?.Invoke(0, ex.Message);
+                }
+            });
+        }
+
+        public void Post(string strURL, string strPostData)
+        {
+            Begin?.Invoke();
+            ThreadPool.QueueUserWorkItem(_ =>
+            {
+                try
+                {
+                    using (var client = new WebClient())
+                    {
+                        client.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
+                        string result = client.UploadString(strURL, strPostData);
+                        End?.Invoke(200, result);
+                    }
+                }
+                catch (WebException ex)
+                {
+                    int code = 0;
+                    if (ex.Response is HttpWebResponse resp)
+                        code = (int)resp.StatusCode;
+                    End?.Invoke(code, ex.Message);
+                }
+                catch (Exception ex)
+                {
+                    End?.Invoke(0, ex.Message);
+                }
+            });
+        }
+    }
+}