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.DecalControls/ChoiceImpl.cs

@@ -0,0 +1,113 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using Decal.Interop.Controls;
+using Decal.Interop.Inject;
+
+namespace Decal.DecalControls
+{
+    [ComVisible(true)]
+    [Guid("E099DC60-0F19-4690-AB7C-8B5834DA286E")]
+    [ClassInterface(ClassInterfaceType.None)]
+    [ComSourceInterfaces("Decal.Interop.Controls.IChoiceEvents\0\0")]
+    [ProgId("DecalControls.Choice")]
+    public class ChoiceImpl : ControlBase, IChoice
+    {
+        public event IChoiceEvents_DestroyEventHandler Destroy;
+        public event IChoiceEvents_ChangeEventHandler Change;
+        public event IChoiceEvents_DropDownEventHandler DropDown;
+
+        private struct ChoiceItem
+        {
+            public string Display;
+            public object Data;
+        }
+
+        private readonly List<ChoiceItem> _items = new List<ChoiceItem>();
+        private int _selected = -1;
+        private bool _dropped;
+        private int _dropLines = 5;
+
+        public void AddChoice(string strDisplay, object vData = null)
+        {
+            _items.Add(new ChoiceItem { Display = strDisplay, Data = vData });
+        }
+
+        public int ChoiceCount => _items.Count;
+
+        public object Data
+        {
+            get => (_selected >= 0 && _selected < _items.Count) ? _items[_selected].Data : null;
+            set
+            {
+                if (_selected >= 0 && _selected < _items.Count)
+                {
+                    var item = _items[_selected];
+                    item.Data = value;
+                    _items[_selected] = item;
+                }
+            }
+        }
+
+        public string Text
+        {
+            get => (_selected >= 0 && _selected < _items.Count) ? _items[_selected].Display : "";
+            set
+            {
+                if (_selected >= 0 && _selected < _items.Count)
+                {
+                    var item = _items[_selected];
+                    item.Display = value ?? "";
+                    _items[_selected] = item;
+                    Invalidate();
+                }
+            }
+        }
+
+        public void RemoveChoice(int nIndex)
+        {
+            if (nIndex >= 0 && nIndex < _items.Count)
+            {
+                _items.RemoveAt(nIndex);
+                if (_selected >= _items.Count) _selected = _items.Count - 1;
+                Invalidate();
+            }
+        }
+
+        public bool Dropped
+        {
+            get => _dropped;
+            set
+            {
+                _dropped = value;
+                if (_dropped) DropDown?.Invoke(ID);
+                Invalidate();
+            }
+        }
+
+        public int Selected
+        {
+            get => _selected;
+            set
+            {
+                if (value >= -1 && value < _items.Count && value != _selected)
+                {
+                    _selected = value;
+                    Invalidate();
+                    Change?.Invoke(ID, _selected);
+                }
+            }
+        }
+
+        public int DropLines { get => _dropLines; set { _dropLines = value; Invalidate(); } }
+
+        public void Clear()
+        {
+            _items.Clear();
+            _selected = -1;
+            Invalidate();
+        }
+
+        protected override void OnDestroy() => Destroy?.Invoke(ID);
+    }
+}