Windows: drag-in install with a per-game d4r.ini

Players extract one ZIP into the game folder, copy their two NVIDIA
DLLs, and start the game from Steam, Epic or a shortcut. No launcher
script is needed; settings live in d4r\d4r.ini.

- Shim player mode: when the launcher has not set D4R_HIP_ROOT and
  d4r.ini sits beside the shim, derive the backend environment from it.
  Codegen flags stay at the Windows-validated values. NVIDIA DLLs must
  match an exact SHA256 in dll-pins.txt, with "you have X, you need Y"
  errors. Rejects a vkd3d/Wine d3d12.dll and code objects built for
  another GPU. [DLSS] Model accepts K or M and is applied by rewriting
  the render preset hints.

- d4r.ini exposes only options that exist on Windows: Model, AsyncInterop,
  ValidateOutput, Log, CacheDir. Invalid values fall back with a note in
  d4r_nvngx.log.

- d4r_nvngx_loader: one _nvngx.dll for all GPUs. It matches the game's
  adapter by LUID and loads _nvngx_<arch>.dll from the same folder.

- OptiScaler patch 0006: relative NvngxPath/NvngxDlssPath/
  NvngxFeaturePath resolve against OptiScaler's folder.

- package-windows-release.ps1 builds the release from the per-target
  game packages and refuses mixed targets or differing shared runtimes.

- Tests: test-player-config.ps1 (ini and DLL-pin decisions, loader
  selection on the local GPU) and test-windows-release-package.ps1.

packaging/windows/OptiScaler.ini

@@ -0,0 +1,27 @@
+; OptiScaler settings for the d4r Windows drag-in release. Values not listed keep OptiScaler's
+; defaults. The DLSS model is chosen in d4r\d4r.ini, not here.
+[Upscalers]
+Dx12Upscaler=dlss
+[FrameGen]
+Enabled=false
+FGInput=nofg
+FGOutput=nofg
+[DLSS]
+Enabled=true
+AllowExternalBackend=true
+RenderPresetOverride=false
+UseGenericAppIdWithDlss=false
+[Libraries]
+; Relative to this folder (needs d4r's OptiScaler with patch 0006).
+NvngxPath=d4r
+NvngxDlssPath=d4r
+NvngxFeaturePath=d4r
+[Hotfix]
+RestoreComputeSignature=false
+RestoreGraphicSignature=false
+ExtendedStateRestore=false
+[Log]
+LogToFile=true
+LogLevel=2
+[Menu]
+DisableSplash=true