Unify config into shell.json and add Noctalia plugin support

default/quickshell/omarchy-shell/Commons/I18n.qml

@@ -0,0 +1,15 @@
+pragma Singleton
+import QtQuick
+
+// Noctalia compat shim. Their plugins normally route translations through
+// pluginApi.tr(), not this singleton, so the stub here mostly exists to
+// satisfy `import qs.Commons` style usage.
+QtObject {
+  readonly property string langCode: "en"
+
+  function tr(key, interp)            { return String(key === undefined ? "" : key) }
+  function trp(key, count, interp)    { return String(key === undefined ? "" : key) }
+  function hasTranslation(key)        { return false }
+
+  signal translationsLoaded()
+}