release: install.sh asks what to install, caches the NVIDIA DLLs and the engine models, and [Engine] defaults to auto

Verified copies go to ~/.cache/d4r: the next game's install copies them instead of downloading or building
again. Enabled = auto (the new default) turns the engine on when d4r/engine holds a model; the shim probes the
nine model folders. build-engine-models.sh gains --exact (NVIDIA's roundings) and --find-proton.

packaging/d4r.ini

@@ -29,7 +29,7 @@ ShowWatermark = false
 Enable = auto
 ; Independent denoiser presets: auto (game choice), default, D, E (transformer) or F (DLSS 4.5).
 ; E and F through NVIDIA's library need a denoiser DLL containing that model (F: 310.9 or later). On the engine
-; ([Engine] Enabled = true) F runs from the model in d4r\engine\rr-f; frames the library serves instead show
+; ([Engine]) F runs from the model in d4r\engine\rr-f; frames the library serves instead show
 ; preset D when the DLL is older (d4r_nvngx.log says so).
 Model = auto
 
@@ -73,11 +73,13 @@ ElideNgxSync = true
 DirectOutput = auto
 
 [Engine]
-; Experimental. Runs DLSS 4 and 4.5 (models K, L and M) on d4r's own Vulkan inference engine instead of NVIDIA's
-; kernels: the game shows the result of the frame it just rendered and [Latency] / [Interop] do not apply.
-; Needs Mesa RADV with VK_KHR_cooperative_matrix and the models in d4r\engine\k, k-ldr, m, m-ldr, l and l-ldr
-; (see D4R_README.txt). Games or settings it does not cover use the normal path; d4r_nvngx.log says why.
-Enabled = false
+; Runs DLSS 4 and 4.5 (models K, L and M) and Ray Reconstruction (D, E and F) on d4r's own Vulkan inference
+; engine instead of NVIDIA's kernels: the faster path, and the game shows the result of the frame it just rendered
+; ([Latency] / [Interop] do not apply). Needs Mesa RADV with VK_KHR_cooperative_matrix and the models install.sh
+; builds in d4r\engine (k, k-ldr, m, m-ldr, l, l-ldr, rr-d, rr-e, rr-f). Games or settings it does not cover,
+; and a device that cannot run it, use the normal path; d4r_nvngx.log says why.
+; auto = on when d4r\engine holds a model, true / false = always / never.
+Enabled = auto
 ; Another model K folder for games with the HDR flag (a path relative to the d4r folder, or a Windows path
 ; such as Z:\home\me\k)
 ModelDir = auto