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.DecalInput/TimerImpl.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Runtime.InteropServices;
+using Decal.Interop.Input;
+
+namespace Decal.DecalInput
+{
+    [ComVisible(true)]
+    [Guid("79497C87-92E1-416B-AE5C-9D6C4C59133C")]
+    [ClassInterface(ClassInterfaceType.None)]
+    [ComSourceInterfaces(typeof(ITimerEvents))]
+    [ProgId("DecalInput.Timer")]
+    public class TimerImpl : IDecalTimer
+    {
+        private object _tag;
+        private bool _running;
+        private int _interval;
+        private uint _startTime;
+
+        public event ITimerEvents_TimeoutEventHandler Timeout;
+
+        public void Start(int Interval)
+        {
+            _interval = Interval;
+            _startTime = GetTickCount();
+            _running = true;
+
+            InputServiceImpl.Instance?.RegisterTimer(this);
+        }
+
+        public void Stop()
+        {
+            _running = false;
+            InputServiceImpl.Instance?.UnregisterTimer(this);
+        }
+
+        public object Tag
+        {
+            get => _tag;
+            set => _tag = value;
+        }
+
+        public bool Running => _running;
+
+        internal bool CheckTimeout(uint currentTime)
+        {
+            if (!_running) return false;
+            if (currentTime - _startTime >= (uint)_interval)
+            {
+                _startTime = currentTime;
+                Timeout?.Invoke((Timer)(object)this);
+                return true;
+            }
+            return false;
+        }
+
+        [DllImport("kernel32.dll")]
+        private static extern uint GetTickCount();
+    }
+}