feat(nixos): migrate system configuration

configs/nixos/modules/desktop/session/hyprland/hyprlock.nix

@@ -0,0 +1,94 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+# The lock screen: a hyprlock session-lock surface the compositor owns.
+let
+  cfg = config.modules.desktop.session.hyprland.hyprlock;
+  user = config.user.name;
+
+  # The hyprlock this module installs, used by the lock keybind below.
+  hyprlock = "${config.home-manager.users.${user}.programs.hyprlock.package}/bin/hyprlock";
+
+  sleepIcon = builtins.fromJSON ''"\udb81\udcb2"'';
+  sleepOffIcon = builtins.fromJSON ''"\udb81\udcb3"'';
+
+  idleLockToggle = pkgs.writeShellScript "lockscreen-idle-inhibit-toggle" ''
+    unit=lockscreen-idle-inhibit.service
+
+    refresh_waybar() {
+      ${pkgs.procps}/bin/pkill -RTMIN+9 waybar >/dev/null 2>&1 || true
+    }
+
+    if ${pkgs.systemd}/bin/systemctl --user is-active --quiet "$unit"; then
+      ${pkgs.systemd}/bin/systemctl --user stop "$unit"
+      refresh_waybar
+      ${pkgs.swayosd}/bin/swayosd-client --custom-message "${sleepIcon}"
+      exit 0
+    fi
+
+    if ${pkgs.systemd}/bin/systemd-run \
+      --user \
+      --collect \
+      --unit=lockscreen-idle-inhibit \
+      --description="Disable idle-triggered screen locking" \
+      ${pkgs.systemd}/bin/systemd-inhibit \
+      --what=idle \
+      --who=lockscreen-hotkey \
+      --why="lock screen disabled by hotkey" \
+      ${pkgs.coreutils}/bin/sleep infinity >/dev/null; then
+      refresh_waybar
+      ${pkgs.swayosd}/bin/swayosd-client --custom-message "${sleepOffIcon}"
+    fi
+  '';
+in
+{
+  options.modules.desktop.session.hyprland.hyprlock.enable = lib.mkEnableOption "the hyprlock lock screen";
+
+  config = lib.mkIf cfg.enable {
+    home-manager.users.${user} = {
+      # Colors and the lock-screen background come from Stylix's hyprlock target,
+      # so only geometry and behaviour are set here.
+      programs.hyprlock = {
+        enable = true;
+
+        settings = {
+          general = {
+            hide_cursor = true;
+            # No progress bar flashes before the field is ready to take input.
+            disable_loading_bar = true;
+          };
+
+          # A centered password field.
+          # Its colors come from the Stylix hyprlock target.
+          input-field = {
+            size = "260, 52";
+            rounding = 8;
+            position = "0, -100";
+            halign = "center";
+            valign = "center";
+          };
+
+          # The current time, above the field.
+          label = {
+            text = "$TIME";
+            font_size = 48;
+            position = "0, 120";
+            halign = "center";
+            valign = "center";
+          };
+        };
+      };
+
+      # Lock on Super+X.
+      # The guard drops the keypress when a locker is already up, so a second
+      # hyprlock never stacks over the first.
+      wayland.windowManager.hyprland.settings.bind = [
+        "$mod, X, exec, ${pkgs.procps}/bin/pidof hyprlock || ${hyprlock}"
+        "$mod CTRL, X, exec, ${idleLockToggle}"
+      ];
+    };
+  };
+}