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/D3DService/NOTES.md

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+# D3DService.DLL
+
+## Origin
+**Entirely new** — no corresponding code in the old source tree.
+Provides a higher-level 3D graphics API that plugins can use to render 3D objects
+in the game world (meshes, 3D text, transformed geometry).
+
+## Binary Facts
+- Size: **262 KB** (the largest of the new native modules)
+- Type: COM in-process server (DLL)
+- Standard 4 COM exports: `DllCanUnloadNow`, `DllGetClassObject`, `DllRegisterServer`, `DllUnregisterServer`
+
+## Key Imports
+| DLL | Functions |
+|-----|-----------|
+| **Inject.DLL** | `BeginSceneO`, `EndSceneO` |
+| **d3dx9_30.dll** | `D3DXCreateRenderToSurface`, `D3DXLoadMeshFromXResource`, `D3DXLoadMeshFromXW`, `D3DXCreateTextW`, `D3DXMatrixTranslation`, `D3DXMatrixRotationY`, and others |
+
+## What It Does
+- Loads `.x` mesh files (from resources or from disk)
+- Creates 3D text geometry
+- Performs matrix transforms (translation, rotation)
+- Renders to off-screen surfaces
+- Essentially a "3D drawing toolkit" layered on top of Inject's scene hooks
+
+## Reconstruction Notes
+- **LOOK AT:** `Managed/Decal.Interop.D3DService/` for the COM interface definitions
+  this DLL must implement. That directory contains **8 decompiled C# files**.
+- There is **no old source** to reference. This must be reimplemented from:
+  1. The COM interfaces defined in the interop assembly
+  2. Knowledge of the D3DX9 API calls it makes
+  3. Understanding of how `BeginSceneO`/`EndSceneO` work (see `Native/Inject/`)
+- This is the most complex new module to reconstruct due to its size and the
+  lack of any prior source code.