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.

tools/windows/dll-pins.txt

@@ -0,0 +1,9 @@
+# NVIDIA DLLs the Windows backend accepts, by exact SHA256. NVIDIA DLLs are
+# never shipped or committed; players copy their own.
+#   dlss = nvngx_dlss.dll (d4r\nvngx_dlss.dll)
+#   ngx  = _nvngx.dll, NVIDIA's NGX core from a display driver (d4r\ngx\_nvngx.dll)
+# status: validated = tested on Windows hardware; anything else is accepted
+# but reported as unvalidated in d4r\d4r_nvngx.log.
+# kind sha256                                                           version       status
+dlss 3975567B8943C53ACCE397F2B72380092F84F162D00B0D2C7D08A1025C563983 310.9.1      validated
+ngx  66767018C36B3BAB46398DADE3ADF173DAA3730FDA75965689EA848C9BC4E79B 32.0.16.1714 validated