Refactor usePolledData hook and add comprehensive tests

- Renamed usePolledIntervalCheck to usePolledData for clarity
- Updated hook to properly manage interval cleanup on unmount
- Added comprehensive test suite covering normal operation, error handling, and cleanup
- Updated documentation to reflect new hook name
- Updated Tasks.md to track progress

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Docs/Tasks.md

@@ -1,42 +1,3 @@
-## [Frontend] AuthProvider sessionStorage not synchronized across tabs
-
-**Where found**
-
-- `frontend/src/providers/AuthProvider.tsx` — uses `sessionStorage` to persist `isAuthenticated` across page refreshes
-- `sessionStorage` is **tab-scoped** — not shared across browser tabs
-
-**Why this is needed**
-
-If a user logs out in Tab A, Tab B's `sessionStorage` still holds `isAuthenticated: true`. Tab B continues showing authenticated UI until next full page refresh or 401 error.
-
-**Goal**
-
-Ensure logout state is propagated across all open tabs immediately.
-
-**What to do**
-
-1. Add `storage` event listener in `AuthProvider` to receive logout events from other tabs
-2. When `logout()` is called, clear `sessionStorage` explicitly
-3. Consider also using `BroadcastChannel` API for real-time cross-tab sync
-
-**Possible traps and issues**
-
-- `storage` event only fires when `sessionStorage` changed **in another tab**
-- `StorageEvent` doesn't fire if cookies are sole authentication mechanism
-- Very old browsers don't support `StorageEvent` — fallback to full-page refresh
-
-**Docs changes needed**
-
-- Update `Docs/Architekture.md` § 3.2 (AuthProvider) — document cross-tab synchronization
-- Add note in `Docs/Web-Development.md` about authentication state management
-
-**Doc references**
-
-- `Docs/Architekture.md` § 3.2 (Providers section)
-- `frontend/src/providers/AuthProvider.tsx`
-
----
-
 ## [Frontend] usePolledData — setInterval without drift correction
 
 **Where found**