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>

NewNativeStubs/SpellFilter/NOTES.md

@@ -0,0 +1,31 @@
+# SpellFilter.DLL
+
+## Origin
+**Entirely new** — no corresponding code in the old source tree.
+A dedicated module for filtering and managing spell-related game data.
+
+## Binary Facts
+- Size: **185 KB**
+- Type: COM in-process server (DLL)
+- Standard 4 COM exports: `DllCanUnloadNow`, `DllGetClassObject`, `DllRegisterServer`, `DllUnregisterServer`
+
+## What It Does
+Provides spell filtering functionality for Asheron's Call — likely parsing spell
+tables from the DAT files, categorizing spells, and letting plugins query/filter
+spells by school, level, name, or other criteria.
+
+## Reconstruction Notes
+- **LOOK AT:** `Managed/Decal.Interop.SpellFilter/` for the COM interface definitions
+  this DLL must implement. That directory contains **20 decompiled C# files** — the
+  most of any interop assembly, suggesting a rich API surface.
+
+- There is **no old source** to reference. This must be reimplemented from:
+  1. The COM interfaces defined in the interop assembly
+  2. Understanding of AC's spell data structures (from the DAT file format)
+  3. Possibly referencing `Native/DecalDat/` for how spell data was already
+     being parsed from DAT files
+  4. Possibly referencing `Native/DecalFilters/` for the general filtering
+     pattern used by Decal
+
+- The 20 interop files suggest this module exposes multiple interfaces for
+  spell tables, individual spells, spell schools, filtering criteria, etc.