niri: add window-rule management

- settings UI for creating, editing, deleting window ruels
- IPC to create a window rule for the currently focused toplevel

fixes #1292

quickshell/Modals/Settings/SettingsContent.qml

@@ -441,5 +441,22 @@ FocusScope {
                     Qt.callLater(() => item.forceActiveFocus());
             }
         }
+
+        Loader {
+            id: windowRulesLoader
+            anchors.fill: parent
+            active: root.currentIndex === 28
+            visible: active
+            focus: active
+
+            sourceComponent: WindowRulesTab {
+                parentModal: root.parentModal
+            }
+
+            onActiveChanged: {
+                if (active && item)
+                    Qt.callLater(() => item.forceActiveFocus());
+            }
+        }
     }
 }

quickshell/Modals/Settings/SettingsSidebar.qml

@@ -252,6 +252,13 @@ Rectangle {
                     "icon": "content_paste",
                     "tabIndex": 23,
                     "clipboardOnly": true
+                },
+                {
+                    "id": "window_rules",
+                    "text": I18n.tr("Window Rules"),
+                    "icon": "select_window",
+                    "tabIndex": 28,
+                    "niriOnly": true
                 }
             ]
         },
@@ -304,6 +311,8 @@ Rectangle {
             return false;
         if (item.hyprlandNiriOnly && !CompositorService.isNiri && !CompositorService.isHyprland)
             return false;
+        if (item.niriOnly && !CompositorService.isNiri)
+            return false;
         if (item.clipboardOnly && (!DMSService.isConnected || DMSService.apiVersion < 23))
             return false;
         return true;