config: never store a null option

Null-valued options serialised into config.json and segfaulted
JsonAdapter on the next launch, killing the shell after load.
Tristate strings (auto/on/off) with boolean fallback.

surfaces/quickshell/modules/common/Config.qml

@@ -13,6 +13,15 @@ Singleton {
     property int readWriteDelay: 50 // milliseconds
     property bool blockWrites: false
 
+    // Tri-state option: "auto" (or anything unrecognized) defers to the
+    // caller's default, "on"/"off" force it. Booleans are honored so old
+    // configs written before the string form keep working.
+    function tristate(value, fallback) {
+        if (value === "on" || value === true) return true;
+        if (value === "off" || value === false) return false;
+        return fallback;
+    }
+
     function setNestedValue(nestedKey, value) {
         let keys = nestedKey.split(".");
         let obj = root.options;
@@ -326,9 +335,12 @@ Singleton {
                 property bool verbose: true
                 property bool vertical: false
                 property JsonObject resources: JsonObject {
-                    // null follows the active bar profile: compact bars rotate
+                    // "auto" follows the active bar profile: compact bars
-                    // one stat; desktop bars render the full resource group.
+                    // rotate one stat; desktop bars render the full group.
-                    property var rotate: null
+                    // "on"/"off" override it. Never null — a null var is
+                    // serialized into config.json and crashes JsonAdapter on
+                    // the next load.
+                    property string rotate: "auto"
                     property int rotateInterval: 4
                     property bool alwaysShowSwap: true
                     property bool alwaysShowCpu: true
@@ -374,10 +386,11 @@ Singleton {
                     property JsonObject notifications: JsonObject {
                         property bool showUnreadCount: false
                     }
-                    // Status icons inside the right-hand pill. Null follows
+                    // Status icons inside the right-hand pill. "auto" follows
                     // the profile: a compact bar drops xkb and bluetooth.
-                    property var showXkb: null
+                    // "on"/"off" override it. Never null — see bar.resources.
-                    property var showBluetooth: null
+                    property string showXkb: "auto"
+                    property string showBluetooth: "auto"
                 }
                 property JsonObject tooltips: JsonObject {
                     property bool clickToShow: false

surfaces/quickshell/modules/ii/bar/BarContent.qml

@@ -511,7 +511,7 @@ Item { // Bar content region
                         }
                     }
                     Loader {
-                        active: Config.options.bar.indicators?.showXkb ?? (root.profile !== "compact")
+                        active: Config.tristate(Config.options.bar.indicators?.showXkb, root.profile !== "compact")
                         visible: active
                         Layout.alignment: Qt.AlignVCenter
                         Layout.rightMargin: indicatorsRowLayout.realSpacing
@@ -543,7 +543,7 @@ Item { // Bar content region
                         color: rightSidebarButton.colText
                     }
                     Loader {
-                        active: (Config.options.bar.indicators?.showBluetooth ?? (root.profile !== "compact")) && BluetoothStatus.available
+                        active: Config.tristate(Config.options.bar.indicators?.showBluetooth, root.profile !== "compact") && BluetoothStatus.available
                         visible: active
                         Layout.leftMargin: indicatorsRowLayout.realSpacing
                         sourceComponent: MaterialSymbol {

surfaces/quickshell/modules/ii/bar/Resources.qml

@@ -25,7 +25,12 @@ MouseArea {
     // explicit config value outranks it. Same precedence as the bar layout:
     // config wins if it says anything, profile decides otherwise.
     property bool autoRotate: false
-    readonly property bool rotate: Config.options.bar.resources?.rotate ?? root.autoRotate
+    readonly property bool rotate: {
+        const v = Config.options.bar.resources?.rotate;
+        if (v === "on" || v === true) return true;
+        if (v === "off" || v === false) return false;
+        return root.autoRotate;
+    }
 
     implicitWidth: rowLayout.implicitWidth + rowLayout.anchors.leftMargin + rowLayout.anchors.rightMargin
     implicitHeight: Appearance.sizes.barHeight