feat(hosts): add lyrathorpe-console, a living-room games machine

New x86_64 host for a 4th-gen Core i7 (Haswell) with a GTX 1070 8 GB,
wired to a television and driven with a Bluetooth controller.

Session: greetd gets an initial_session, so the machine autologins into
the gamescope Steam session at boot with no greeter and no keyboard.
Quitting Steam falls back to greetd's default_session (ReGreet), where
the ordinary Sway session is available for keyboard-and-mouse work.

Graphics: the GTX 1070 is Pascal, so it needs driver branch 580
(nvidiaPackages.legacy_580) like the Mac Pro's Quadro P400 -- the
nixpkgs default (production, 595.x) dropped Pascal support.

Games: RetroArch built through retroarch-bare.wrapper with 17 cores
covering NES through PS2, GameCube and Wii; Clone Hero; and Steam with
Proton-GE and protontricks. RetroArch's menu toggle is bound to L3+R3,
without which there is no way to exit a running core on a machine with
no keyboard.

Proton prerequisites beyond what programs.steam already arranges: the
esync file-descriptor hard limit is raised from systemd's default
524288 to 1048576 (soft limit untouched), and Proton-GE is wired in via
extraCompatPackages. vm.max_map_count already defaults high enough in
nixpkgs and needs no override.

Content lives in a shared /srv/games tree created by systemd.tmpfiles,
laid out one directory per system under roms/ using the libretro/ES-DE
naming convention, plus bios/, saves/, states/, a Steam library folder
and Clone Hero's songs. RetroArch is pointed at it declaratively.

hardware-configuration.nix is a placeholder, not a hardware scan: the
machine is not installed yet. It assumes partition labels `nixos` and
`BOOT` and must be replaced with nixos-generate-config output.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

hosts/Console/nvidia.nix

@@ -0,0 +1,54 @@
+# NVIDIA GeForce GTX 1070 8 GB (Pascal, GP104): proprietary driver for the
+# gamescope Steam session and the Sway desktop.
+#
+# Driver branch: 580 (nvidiaPackages.legacy_580), NOT the nixpkgs default
+# (`production`, currently 595.x). 580 is the last branch that supports
+# Maxwell/Pascal/Volta -- NVIDIA keeps it as an LTS branch to Aug 2028 -- and a
+# newer branch simply will not drive this card. Same constraint as the Mac Pro's
+# Quadro P400; see hosts/MacPro31/nvidia.nix.
+#
+# The driver is unfree, so it is not in the binary cache: the kernel module is
+# compiled locally on every kernel bump.
+{ config, ... }:
+
+{
+  # Selects the proprietary driver; the module blacklists nouveau/nvidiafb and
+  # loads nvidia-uvm via a modprobe softdep. Naming is historical -- this option
+  # drives the kernel/driver choice on Wayland hosts too, which is why it is set
+  # on a machine that runs no X server.
+  services.xserver.videoDrivers = [ "nvidia" ];
+
+  hardware.nvidia = {
+    package = config.boot.kernelPackages.nvidiaPackages.legacy_580;
+    # Required for Wayland: sets nvidia-drm.modeset=1 (and fbdev=1), without
+    # which neither gamescope nor wlroots gets a usable GBM device and both the
+    # Steam session and Sway fail to start.
+    modesetting.enable = true;
+    # The open kernel modules need Turing or later; Pascal must use the closed
+    # ones. Explicit because the option has no default on driver >= 560.
+    open = false;
+  };
+
+  # The NVIDIA module only puts these in boot.kernelModules when
+  # services.xserver.enable is true, which is false on this Wayland-only host --
+  # so load them explicitly rather than relying on udev modalias autoloading.
+  # nvidia_uvm is deliberately absent: the module's modprobe softdep pulls it in
+  # after the GPU device exists, which is the supported ordering.
+  boot.kernelModules = [
+    "nvidia"
+    "nvidia_modeset"
+    "nvidia_drm"
+  ];
+
+  # wlroots refuses the proprietary NVIDIA driver unless told to proceed. The
+  # greeter's compositor (cage) and gamescope have no such check; only Sway
+  # needs the flag, which the module bakes into the wrapper the session's
+  # .desktop file runs.
+  programs.sway.extraOptions = [ "--unsupported-gpu" ];
+
+  # 32-bit driver libraries for 32-bit Steam titles and Proton's 32-bit
+  # prefixes: hardware.graphics.enable32Bit pulls in the matching lib32 NVIDIA
+  # userspace. programs.steam (./gaming.nix) sets it too; stated here as well so
+  # the GPU's 32-bit story lives with the rest of the GPU config.
+  hardware.graphics.enable32Bit = true;
+}