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>

Native/DenAgent/AutoUpdate.h

@@ -0,0 +1,70 @@
+#ifndef __AUTOUPDATE_H__
+#define __AUTOUPDATE_H__
+
+class DownloadAgent {
+public:
+	static bool downloadFile(std::string remoteFile, std::string localFile);
+
+	DownloadAgent();
+
+	void scheduleDownload(std::string remoteFile, std::string localFile);
+	bool runDownloads();
+
+private:
+	struct DownloadSlot {
+		std::string remoteFile, localFile;
+	};
+
+	std::list<DownloadSlot> m_ScheduledDownloads;
+};
+
+enum AutoUpdateType {
+	AU_TYPE_XML,
+	AU_TYPE_DLL,
+	AU_TYPE_BETADLL
+};
+
+class UpdateRequirement
+{
+public:
+	UpdateRequirement(std::string File, std::string Version):
+		sFile(File), sVers(Version)	{ }
+	std::string sFile;
+	std::string sVers;
+};
+
+class AutoUpdateSource {
+public:
+	AutoUpdateSource(std::string decalPath, AutoUpdateType type, std::string localTarget, std::string remoteSource, std::string requiredVersion);
+
+	bool needsUpdating();
+	std::string getSource();
+	std::string getDestination();
+	AutoUpdateType getType();
+	bool isOutDatedVersion(std::string sFile, int nMajor, int nMinor, int nPatch, int nBuild);
+	void AddRequirement(UpdateRequirement reqUpdate);
+
+private:
+	std::string m_LocalTarget;
+	std::string m_RemoteSource;
+	std::string m_RequiredVersion;
+	std::string m_DecalDir;
+	AutoUpdateType m_Type;
+	std::vector<UpdateRequirement> m_Requirements;
+};
+
+class AutoUpdate {
+public:
+	AutoUpdate(std::string decalDir);
+
+	bool initialiseFromXML(std::string remoteXML);
+	bool needsUpdate();
+	bool performUpdate();
+
+private:
+	std::string m_LocalXML, m_RemoteXML;
+	std::string m_DecalDir;
+	std::list<AutoUpdateSource> m_RemoteSources;
+};
+
+#endif