flake: export nixosModules.gaming for guests with their own hardware

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

readme.md

@@ -139,6 +139,47 @@ After this succeeds, the plain `update` alias works from then on.
 
 ---
 
+## Running the desktop on someone else's machine
+
+`nixosModules.gaming` is the whole FredOS-Gaming desktop — Hyprland, quickshell,
+stylix theming, Steam, the lot — with `hosts/hardware/FredOS-Gaming.nix` left
+out. Import it from your own flake alongside your own
+`/etc/nixos/hardware-configuration.nix`, which stays on your machine and never
+touches this repo, so `nix flake update` keeps pulling my changes without ever
+overwriting your disks and GPU:
+
+```nix
+{
+  inputs.fredos.url = "git+https://forg.gregersen.it/rope/nixos";
+
+  outputs = { self, fredos, ... }: {
+    nixosConfigurations.mine = fredos.inputs.nixpkgs.lib.nixosSystem {
+      modules = [
+        fredos.nixosModules.gaming
+        ./hardware-configuration.nix
+      ];
+    };
+  };
+}
+```
+
+Then `sudo nixos-rebuild switch --flake .#mine`.
+
+Notes:
+
+- The hostname stays `FredOS-Gaming` — every module in here is gated on it, so
+  changing it switches the desktop off.
+- The module drops my build server and my SSH keys, and defaults
+  `system.stateVersion`, `nixpkgs.hostPlatform` and systemd-boot so a stock
+  `hardware-configuration.nix` is enough. All `mkDefault`, so override freely.
+- The CachyOS kernel and its binary cache live in the hardware file, so you
+  won't get them. Copy those lines out of `hosts/hardware/FredOS-Gaming.nix` if
+  you want them.
+- The user is `fred` with passwordless sudo. `passwd fred` after the first
+  switch.
+- My monitor layout (`DP-3`, 3440x1440@180) is in `hosts/FredOS-Gaming.nix`;
+  override `wayland.windowManager.hyprland.settings.monitor` for yours.
+
 ## Flake inputs
 
 | Input | Source |