fix: resolve React hydration errors preventing app startup

[EnthusiAD]

Description

This PR resolves critical "Hydration failed" errors that were causing the application to crash or behave inconsistently on initial load (especially for logged-in users). The issue was caused by accessing client-side APIs (window, localStorage, sessionStorage) directly during the server-side rendering (SSR) pass.

Changes

src/components/Header/Header.jsx

• Refactor: Moved authentication checks (isAuth, isAdmin) and user data retrieval (getUserName, getAllGroups) into a useEffect hook to ensure they only run on the client.
• State Management: Introduced local state initialized to safe default values (false/null) to ensure the initial server render matches the client render.

src/components/Footer/Footer.jsx

• Refactor: Moved version retrieval logic from getSessionStorage into a useEffect hook.
• Fix: Initialized version state as null to prevent hydration mismatches during the initial paint.

How to test

1. Clean Setup: Clear LocalStorage (Application > Storage > Clear All) and refresh the page.
2. Verify Login: Log in (or inject a valid token) to access the Dashboard.
3. Check Console: Verify that the red "Hydration failed" or "Text content does not match server-rendered HTML" errors no longer appear in the browser console.
4. Visual Check: Confirm that the Header user menu and Footer version number appear correctly after the page loads.