workspaces: auto-detect Hyprland alongside i3/Sway

Drive the switcher from Hyprland.workspaces when HYPRLAND_INSTANCE_SIGNATURE
is set, else fall back to I3.workspaces. The ?: model binding only evaluates
the taken branch, so the unused backend singleton is never instantiated (no
stray IPC). Both workspace types share the same shape (name/active/focused/
urgent/monitor.name/activate()), so the chip renderer is unchanged.

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

widgets/Workspaces.qml

@@ -2,25 +2,34 @@ import QtQuick
 import QtQuick.Layouts
 import Quickshell
 import Quickshell.I3
+import Quickshell.Hyprland
 import "../config"
 
-// Sway/i3 workspace switcher for a single monitor.
+// Workspace switcher for a single monitor. Works on both Sway/i3 and Hyprland:
+// the compositor is detected once from its instance env var, and the matching
+// Quickshell backend model is used. The two backends expose the same item shape
+// (name / active / focused / urgent / monitor.name / activate()), so a single
+// chip renderer covers both. The `?:` on `model` only evaluates the taken
+// branch, so the unused backend singleton is never instantiated (no stray IPC).
 Row {
     id: root
     required property var screen   // ShellScreen this bar lives on
     spacing: Theme.gap
 
-    // Name of the i3/sway output this bar is on, used to filter workspaces.
+    // Which compositor are we under? Hyprland always exports this signature.
+    readonly property bool isHyprland: !!Quickshell.env("HYPRLAND_INSTANCE_SIGNATURE")
+
+    // Name of the output this bar is on, used to filter workspaces.
     readonly property string monitorName: screen ? screen.name : ""
 
     Repeater {
-        model: I3.workspaces
+        model: root.isHyprland ? Hyprland.workspaces : I3.workspaces
 
         Rectangle {
             id: chip
             required property var modelData
-            // only show workspaces belonging to this monitor
+            // only show workspaces belonging to this monitor. Both I3Workspace
-            // I3Workspace.monitor is an I3Monitor object, so compare its name
+            // and HyprlandWorkspace expose .monitor as an object with a .name.
             visible: modelData.monitor && modelData.monitor.name === root.monitorName
             width: visible ? Math.max(height, label.implicitWidth + 16) : 0
             height: Theme.barHeight - Theme.gap * 2