Fix what the 0.6.0 review found, and ship DLSS Frame Generation in the launcher release.

The commit census of the perf trace walked the address space on the presenting thread outside mem_census, which
brought back the hitch mem_census was added to remove; it now runs only with mem_census = 1. DLSS's output pass at
the mode's share fell back to no pass at all when the scene was not at that share (the first presents, a dynamic
resolution step): after such a frame the first pass wider than the scene is taken again for 120 frames. The launcher's
nx2navi.ini editor no longer rewrites a file it cannot read, keeps the byte order mark and bytes that are not UTF-8,
reads an empty line as the game does, and leaves no temporary file behind. The build kit carries the two modules
build_game.py imports on Linux, the Linux steps list the right packages and Python, and stale comments and notes are
corrected (Discord on by default, two prebuild threads, Enhanced HDR gone).

DLSS Frame Generation needs nx2navi_dlssg.dll, NVIDIA Streamline's runtime and nvngx_dlssg.dll beside the game, which
no release carried, so the menu offered it and the game turned it off. tools/make_launcher.py --dlssg and --streamline
put them with their licences and a notice in the release's bin/dlssg/, and tools/make_game.py place_dlssg copies the
whole set beside the game. THIRD_PARTY_NOTICES.md has the row; the notes and README say RTX 40 and 50.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -32,7 +32,7 @@ Report problems as issues, following [CONTRIBUTING.md](CONTRIBUTING.md).
 - Upscaling and anti-aliasing: NVIDIA DLSS (DLAA, Quality, Balanced, Performance, Ultra Performance; RTX GPUs) or
   AMD FSR 3.1 (Native AA and the same modes; any GPU), which render the 3D scene at the mode's share and keep the HUD
   sharp; or AMD FSR 1 or bilinear scaling to the window, with a sharpness setting; black bars or stretch
-- Frame generation: NVIDIA DLSS Frame Generation (RTX GPUs, paced with Reflex) or AMD FSR 3.1 (any GPU), a generated
+- Frame generation: NVIDIA DLSS Frame Generation (RTX 40 and 50 GPUs, paced with Reflex) or AMD FSR 3.1 (any GPU), a generated
   frame between every two the game draws, with the HUD kept out of it, for about twice the frame rate on a fast
   display; in a window of another shape than the picture, frames are generated inside the picture only, so the black
   bars stay clean. The frame limit can also be handed to RivaTuner Statistics Server