settings: treat an unversioned settings file as the current format

fixes #3956
port 2.0

quickshell/Common/SettingsData.qml

@@ -1836,7 +1836,7 @@ Singleton {
         let obj = _getSettingsObjectFromFiles();
         let loadedSettings = JSON.stringify(obj);
 
-        const oldVersion = obj?.configVersion ?? 0;
+        const oldVersion = obj?.configVersion ?? settingsConfigVersion;
         if (oldVersion > settingsConfigVersion) {
             newerSettingsBackup.path = `${_configDir}/dms/settings.v${oldVersion}.json`;
             newerSettingsBackup.setText(JSON.stringify(obj, null, 2));

quickshell/Common/settings/SettingsStore.js

@@ -232,8 +232,11 @@ function migrateToVersion(obj, targetVersion) {
     if (!obj)
         return null;
 
+    // hand-written and nix-generated files carry no version and are authored against the current format
+    if (obj.configVersion === undefined)
+        return null;
     var settings = JSON.parse(JSON.stringify(obj));
-    var currentVersion = settings.configVersion || 0;
+    var currentVersion = settings.configVersion;
 
     if (currentVersion >= targetVersion) {
         return null;