waybar: add a power menu module

Click the ⏻ glyph on the right edge of the bar; a fuzzel dmenu pops up
with Lock / Logout / Reboot / Shutdown. Lock runs hyprlock, logout
exits Hyprland, the others go through systemctl. Hover state turns the
icon base08 (red) as a soft warning.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

settings/hyprland.nix

@@ -298,7 +298,7 @@
 
           modules-left   = [ "hyprland/workspaces" ];
           modules-center = [ "clock" ];
-          modules-right  = [ "pulseaudio" "network" "tray" ];
+          modules-right  = [ "pulseaudio" "network" "tray" "custom/power" ];
 
           "hyprland/workspaces" = {
             format = "{name}";
@@ -335,6 +335,21 @@
             icon-size = 16;
             spacing = 8;
           };
+
+          "custom/power" = {
+            format = "⏻";
+            tooltip = false;
+            on-click = "${pkgs.writeShellScript "power-menu" ''
+              choice=$(printf "Lock\nLogout\nReboot\nShutdown" \
+                | ${pkgs.fuzzel}/bin/fuzzel --dmenu --prompt="Power: " --lines=4 --width=12)
+              case "$choice" in
+                Lock)     ${pkgs.hyprlock}/bin/hyprlock ;;
+                Logout)   hyprctl dispatch exit ;;
+                Reboot)   systemctl reboot ;;
+                Shutdown) systemctl poweroff ;;
+              esac
+            ''}";
+          };
         };
 
         # Colour tokens (@base00..@base0F) are injected by stylix's waybar
@@ -382,7 +397,8 @@
 
           #pulseaudio,
           #network,
-          #tray {
+          #tray,
+          #custom-power {
             padding: 0 10px;
             color: @base05;
           }
@@ -392,9 +408,17 @@
             color: @base03;
           }
 
-          #tray {
+          #custom-power:hover {
+            color: @base08;
+          }
+
+          #custom-power {
             margin-right: 6px;
           }
+
+          #tray {
+            margin-right: 0;
+          }
         '';
       };
     };