chore(install): stop writing distro-default config into system.nix

console.useXkbConfig and boot.initrd.systemd.enable are set distro-wide
(lib.mkDefault true in modules/nixos/default.nix, since the LUKS-keymap
fix), so the installer rewriting them in the generated system.nix was
redundant. Drop them there and from the offline-pin test fixture in
flake.nix — the nomarchy module still defaults them on, so the closure
(and the pin set) is unchanged; verified the values still resolve true
and `nix flake check` passes. Only the machine-specific xkb layout is
written now. Adjusts the README keyboard-option wording to match.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pkgs/nomarchy-install/nomarchy-install.sh

@@ -444,15 +444,14 @@ cat > "$FLAKE_DIR/system.nix" <<EOF
   time.timeZone = "$TIMEZONE";
   i18n.defaultLocale = "$LOCALE";
 
-  # One keyboard layout everywhere: xkb is the source of truth, the
-  # virtual console derives from it (greeter/ttys), and the systemd
-  # initrd applies it to the LUKS passphrase prompt too (the classic
-  # script initrd cannot). The Hyprland session reads the same layout
-  # from nomarchy.keyboard.* in home.nix.
+  # One keyboard layout everywhere: xkb is the source of truth, and the
+  # distro defaults (console.useXkbConfig + the systemd initrd, set in
+  # the nomarchy module) derive the virtual console and the LUKS
+  # passphrase prompt from it — so only the chosen layout is written here.
+  # The Hyprland session reads the same layout from nomarchy.keyboard.* in
+  # home.nix.
   services.xserver.xkb.layout = "$KB_LAYOUT";
   services.xserver.xkb.variant = "$KB_VARIANT";
-  console.useXkbConfig = true;
-  boot.initrd.systemd.enable = true;
 
   # Your login user — \`username\` flows in from flake.nix automatically.
   users.users.\${username} = {