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.DHS/HotkeySystemImpl.cs

@@ -0,0 +1,161 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using Decal.Interop.Core;
+using Decal.Interop.DHS;
+
+namespace Decal.DHS
+{
+    internal class RegisteredHotkey
+    {
+        public string PluginCookie;
+        public HotkeyImpl Hotkey;
+    }
+
+    [ComVisible(true)]
+    [Guid("6B6B9FA8-37DE-4FA3-8C60-52BD6A2F9855")]
+    [ClassInterface(ClassInterfaceType.None)]
+    [ComSourceInterfaces(typeof(_IHotkeySystemEvents))]
+    [ProgId("DHS.HotkeySystem")]
+    public class HotkeySystemImpl : IHotkeySystem, IDecalService
+    {
+        private readonly List<RegisteredHotkey> _hotkeys = new List<RegisteredHotkey>();
+        private readonly Dictionary<object, IDHSHotkeyEvents> _connectedPlugins = new Dictionary<object, IDHSHotkeyEvents>();
+
+        // COM event — raised when a hotkey fires
+        public event _IHotkeySystemEvents_HotkeyEventEventHandler HotkeyEvent;
+
+        public void AddHotkey(string szPlugin, Hotkey pHotkey)
+        {
+            var impl = pHotkey as HotkeyImpl;
+            if (impl == null)
+            {
+                // Wrap foreign IHotkey implementation
+                impl = new HotkeyImpl
+                {
+                    EventTitle = ((IHotkey)pHotkey).EventTitle,
+                    EventDescription = ((IHotkey)pHotkey).EventDescription,
+                    AltState = ((IHotkey)pHotkey).AltState,
+                    ControlState = ((IHotkey)pHotkey).ControlState,
+                    ShiftState = ((IHotkey)pHotkey).ShiftState,
+                    VirtualKey = ((IHotkey)pHotkey).VirtualKey
+                };
+            }
+
+            _hotkeys.Add(new RegisteredHotkey
+            {
+                PluginCookie = szPlugin,
+                Hotkey = impl
+            });
+        }
+
+        public bool QueryHotkey(string bstrTitle)
+        {
+            foreach (var rh in _hotkeys)
+            {
+                if (string.Equals(rh.Hotkey.EventTitle, bstrTitle, StringComparison.OrdinalIgnoreCase))
+                    return true;
+            }
+            return false;
+        }
+
+        public Hotkey QueryHotkeyEx(string szPluginCookie, string szTitle)
+        {
+            foreach (var rh in _hotkeys)
+            {
+                if (string.Equals(rh.PluginCookie, szPluginCookie, StringComparison.OrdinalIgnoreCase) &&
+                    string.Equals(rh.Hotkey.EventTitle, szTitle, StringComparison.OrdinalIgnoreCase))
+                {
+                    return (Hotkey)(object)rh.Hotkey;
+                }
+            }
+            return null;
+        }
+
+        public void Connect(object pPlugin)
+        {
+            // Plugin implements IDHSHotkeyEvents for receiving hotkey notifications
+            var events = pPlugin as IDHSHotkeyEvents;
+            if (events != null)
+            {
+                _connectedPlugins[pPlugin] = events;
+            }
+        }
+
+        public void DeleteHotkey(string szPluginCookie, string szHotkeyName)
+        {
+            _hotkeys.RemoveAll(rh =>
+                string.Equals(rh.PluginCookie, szPluginCookie, StringComparison.OrdinalIgnoreCase) &&
+                string.Equals(rh.Hotkey.EventTitle, szHotkeyName, StringComparison.OrdinalIgnoreCase));
+        }
+
+        /// <summary>
+        /// Called by the input system when a key combination matches a registered hotkey.
+        /// Fires the HotkeyEvent and notifies connected plugins.
+        /// </summary>
+        internal bool FireHotkey(string eventTitle)
+        {
+            bool eat = false;
+
+            // Fire COM connection point event
+            HotkeyEvent?.Invoke(eventTitle, ref eat);
+            if (eat) return true;
+
+            // Notify connected plugins via IDHSHotkeyEvents
+            foreach (var plugin in _connectedPlugins.Values)
+            {
+                try
+                {
+                    if (plugin.OnHotkey(eventTitle))
+                        return true;
+                }
+                catch
+                {
+                    // Plugin error — don't propagate
+                }
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Check if a key press matches any registered hotkey and fire it.
+        /// </summary>
+        internal bool ProcessKey(int virtualKey, bool alt, bool ctrl, bool shift)
+        {
+            foreach (var rh in _hotkeys)
+            {
+                var hk = rh.Hotkey;
+                if (hk.VirtualKey == virtualKey &&
+                    hk.AltState == alt &&
+                    hk.ControlState == ctrl &&
+                    hk.ShiftState == shift)
+                {
+                    if (FireHotkey(hk.EventTitle))
+                        return true;
+                }
+            }
+            return false;
+        }
+
+        // IDecalService implementation
+        public void Initialize(DecalCore pDecal)
+        {
+            // DHS doesn't need DecalCore reference directly
+        }
+
+        public void BeforePlugins()
+        {
+        }
+
+        public void AfterPlugins()
+        {
+        }
+
+        public void Terminate()
+        {
+            _hotkeys.Clear();
+            _connectedPlugins.Clear();
+        }
+    }
+}