feat: enhance CurrentDutyView with loading skeletons and improved localization

- Added Skeleton components to CurrentDutyView for better loading state representation.
- Updated localization messages to include new labels for remaining time display.
- Refactored remaining time display logic for clarity and improved user experience.

webapp-next/src/lib/current-duty.test.ts

@@ -3,7 +3,7 @@
  * Ported from webapp/js/currentDuty.test.js.
  */
 
-import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { describe, it, expect, vi } from "vitest";
 import { getRemainingTime, findCurrentDuty } from "./current-duty";
 import type { DutyWithUser } from "@/types";