fix: actually register the czech language (#5189)

frontend/src/components/settings/Languages.vue

@@ -19,6 +19,7 @@ export default {
       hu: "Magyar",
       ar: "العربية",
       ca: "Català",
+      cs: "Čeština",
       de: "Deutsch",
       el: "Ελληνικά",
       en: "English",

frontend/src/i18n/index.ts

@@ -26,6 +26,7 @@ import("dayjs/locale/uk");
 import("dayjs/locale/vi");
 import("dayjs/locale/zh-cn");
 import("dayjs/locale/zh-tw");
+import("dayjs/locale/cs");
 
 // All i18n resources specified in the plugin `include` option can be loaded
 // at once using the import syntax