feat: enhance admin page and testing functionality

- Updated admin page to include navigation buttons for month selection, improving user experience.
- Refactored `AdminDutyList` to group duties by date, enhancing the display and organization of duties.
- Improved error handling in `ReassignSheet` by using i18n keys for error messages, ensuring better localization support.
- Enhanced tests for admin page and components to reflect recent changes, ensuring accuracy in functionality and accessibility.
- Added event dispatch for configuration loading in the app configuration, improving integration with the Telegram Mini App.

webapp-next/src/hooks/use-app-init.ts

@@ -7,7 +7,6 @@
 
 import { useEffect } from "react";
 import { useAppStore } from "@/store/app-store";
-import { getLang } from "@/i18n/messages";
 import { useTranslation } from "@/i18n/use-translation";
 import { RETRY_DELAY_MS } from "@/lib/constants";
 
@@ -19,24 +18,18 @@ export interface UseAppInitParams {
 }
 
 /**
- * Syncs language from backend config, applies document lang/title, handles access denied
- * when not allowed, and routes to current duty view when opened via startParam=duty.
+ * Applies document lang/title from store (when this hook runs, e.g. main page).
+ * Handles access denied when not allowed and routes to current duty view when opened via startParam=duty.
+ * Language is synced from window.__DT_LANG in TelegramProvider (all routes).
  */
 export function useAppInit({ isAllowed, startParam }: UseAppInitParams): void {
-  const setLang = useAppStore((s) => s.setLang);
   const lang = useAppStore((s) => s.lang);
   const setAccessDenied = useAppStore((s) => s.setAccessDenied);
   const setLoading = useAppStore((s) => s.setLoading);
   const setCurrentView = useAppStore((s) => s.setCurrentView);
   const { t } = useTranslation();
 
-  // Sync lang from backend config (window.__DT_LANG).
-  useEffect(() => {
-    if (typeof window === "undefined") return;
-    setLang(getLang());
-  }, [setLang]);
-
-  // Apply lang to document (title and html lang) for accessibility and i18n.
+  // Apply lang to document (title and html lang) when main page is mounted (tests render Page without TelegramProvider).
   useEffect(() => {
     if (typeof document === "undefined") return;
     document.documentElement.lang = lang;