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/ScrollerImpl.cs

@@ -0,0 +1,67 @@
+using System.Runtime.InteropServices;
+using Decal.Interop.Controls;
+using Decal.Interop.Core;
+using Decal.Interop.Inject;
+
+namespace Decal.DecalControls
+{
+    [ComVisible(true)]
+    [Guid("8FC80D21-1731-4816-9AD3-B0364D5F2C27")]
+    [ClassInterface(ClassInterfaceType.None)]
+    [ComSourceInterfaces("Decal.Interop.Controls.IScrollerEvents\0\0")]
+    [ProgId("DecalControls.Scroller")]
+    public class ScrollerImpl : ControlBase, IScroller
+    {
+        public event IScrollerEvents_DestroyEventHandler Destroy;
+        public event IScrollerEvents_ChangeEventHandler Change;
+
+        private tagSIZE _area;
+        private tagPOINT _offset;
+        private tagSIZE _increments = new tagSIZE { cx = 1, cy = 1 };
+        private bool _horizontalEnabled = true;
+        private bool _verticalEnabled = true;
+
+        public tagSIZE Viewport
+        {
+            get
+            {
+                var pos = Position;
+                return new tagSIZE { cx = pos.right - pos.left, cy = pos.bottom - pos.top };
+            }
+        }
+
+        public tagSIZE Area { get => _area; set { _area = value; Invalidate(); } }
+        public bool HorizontalEnabled { get => _horizontalEnabled; set { _horizontalEnabled = value; Invalidate(); } }
+        public bool VerticalEnabled { get => _verticalEnabled; set { _verticalEnabled = value; Invalidate(); } }
+
+        public tagPOINT Offset
+        {
+            get => _offset;
+            set
+            {
+                _offset = value;
+                Invalidate();
+                Change?.Invoke(ID, _offset.x, _offset.y);
+            }
+        }
+
+        public tagSIZE Increments { get => _increments; set => _increments = value; }
+
+        public void CreateClient(ILayer pChild) { }
+
+        public void ScrollTo(ref tagPOINT ptOffset)
+        {
+            _offset = ptOffset;
+            Invalidate();
+            Change?.Invoke(ID, _offset.x, _offset.y);
+        }
+
+        public void ResetScroller()
+        {
+            _offset = default;
+            Invalidate();
+        }
+
+        protected override void OnDestroy() => Destroy?.Invoke(ID);
+    }
+}