feat(demo): add language selection window and update localization keys

data/i18n/i18n.yaml

@@ -1,5 +1,5 @@
 ---
-curId: 8
+curId: 10
 descriptions:
   test-2: ""
   test-1: "aaa"
@@ -19,6 +19,8 @@ languages:
     test-6: "OK"
     test-7: "Toggle Audio"
     test-8: "ScrollArea Demo"
+    test-9: "Select Language"
+    test-10: "Current: "
   de:
     test-1: "hallo"
     test-2: "welt"
@@ -28,6 +30,8 @@ languages:
     test-6: "Ok"
     test-7: "Audio umschalten"
     test-8: "ScrollArea Demo"
+    test-9: "Sprache auswählen"
+    test-10: "Aktuell: "
 languagesInfo:
   en:
     name: "English"