feat: enhance testing and admin page functionality

- Mocked `useRouter` from `next/navigation` in tests to improve routing behavior during testing.
- Updated admin page tests to reflect changes in title display and removed unnecessary back link check.
- Refactored admin page header to improve accessibility and layout, displaying month and year more clearly.
- Removed unused imports and components to streamline code and enhance maintainability.

webapp-next/src/components/CalendarPage.tsx

@@ -6,14 +6,14 @@
 "use client";
 
 import { useRef, useState, useEffect, useCallback } from "react";
-import Link from "next/link";
+import { useRouter } from "next/navigation";
+import { settingsButton } from "@telegram-apps/sdk-react";
 import { useAppStore } from "@/store/app-store";
 import { useShallow } from "zustand/react/shallow";
 import { useMonthData } from "@/hooks/use-month-data";
 import { useSwipe } from "@/hooks/use-swipe";
 import { useStickyScroll } from "@/hooks/use-sticky-scroll";
 import { useAutoRefresh } from "@/hooks/use-auto-refresh";
-import { useTranslation } from "@/i18n/use-translation";
 import { CalendarHeader } from "@/components/calendar/CalendarHeader";
 import { CalendarGrid } from "@/components/calendar/CalendarGrid";
 import { DutyList } from "@/components/duty/DutyList";
@@ -80,7 +80,7 @@ export function CalendarPage({ isAllowed, initDataRaw }: CalendarPageProps) {
     }))
   );
 
-  const { t } = useTranslation();
+  const router = useRouter();
 
   const { retry } = useMonthData({
     initDataRaw,
@@ -138,6 +138,35 @@ export function CalendarPage({ isAllowed, initDataRaw }: CalendarPageProps) {
     }
   }, [loading, accessDenied, setAppContentReady]);
 
+  // Show native Settings button in Telegram context menu for admins; click navigates to /admin.
+  useEffect(() => {
+    if (!isAdmin) return;
+    let offClick: (() => void) | undefined;
+    try {
+      if (settingsButton.mount.isAvailable()) {
+        settingsButton.mount();
+      }
+      if (settingsButton.show.isAvailable()) {
+        settingsButton.show();
+      }
+      if (settingsButton.onClick.isAvailable()) {
+        offClick = settingsButton.onClick(() => router.push("/admin"));
+      }
+    } catch {
+      // Non-Telegram environment; SettingsButton not available.
+    }
+    return () => {
+      try {
+        if (typeof offClick === "function") offClick();
+        if (settingsButton.hide.isAvailable()) {
+          settingsButton.hide();
+        }
+      } catch {
+        // Ignore cleanup errors in non-Telegram environment.
+      }
+    };
+  }, [isAdmin, router]);
+
   return (
     <div className="content-safe mx-auto flex min-h-[var(--tg-viewport-stable-height,100vh)] w-full max-w-[var(--max-width-app)] flex-col bg-background px-3 pb-6">
       <div
@@ -149,16 +178,6 @@ export function CalendarPage({ isAllowed, initDataRaw }: CalendarPageProps) {
           disabled={navDisabled}
           onPrevMonth={handlePrevMonth}
           onNextMonth={handleNextMonth}
-          trailingContent={
-            isAdmin ? (
-              <Link
-                href="/admin"
-                className="text-sm text-accent hover:underline focus-visible:outline-accent rounded"
-              >
-                {t("admin.link")}
-              </Link>
-            ) : undefined
-          }
         />
         <CalendarGrid
           currentMonth={currentMonth}