Add default fallback city (fixes #199), add beginning of UpdateService

Weather: always fallback to "Tokyo" if the city name is empty
UpdateService: simple versioning control

Services/UpdateService.qml

@@ -0,0 +1,30 @@
+pragma Singleton
+
+import QtQuick
+import Quickshell
+import qs.Commons
+
+Singleton {
+  id: root
+
+  // Public properties
+  property string baseVersion: "v2.4.1"
+  property bool isRelease: false
+
+  property string currentVersion: isRelease ? baseVersion : baseVersion + "-dev"
+
+  // Internal helpers
+  function getVersion() {
+    return root.currentVersion
+  }
+
+  function checkForUpdates() {
+    // TODO: Implement update checking logic
+    Logger.log("UpdateService", "Checking for updates...")
+  }
+
+  function init() {
+    // Ensure the singleton is created
+    Logger.log("UpdateService", "Version:", root.currentVersion)
+  }
+}