fix(navigation): clean up leaked global scroll listeners

[Manishnemade12]

Description

Fixes memory leaks caused by uncleaned global scroll listeners in SPA navigation flows.

Closes : #7611

Root Cause

Two components attached window.addEventListener("scroll", ...) using anonymous callbacks inside useEffect without corresponding cleanup, so listeners accumulated across route transitions.

What Changed

• Added a named handleScroll function and cleanup return in src/sections/General/Navigation/index.js.
• Added a named handleHeaderScroll function and cleanup return in src/sections/Company/Brand/index.js.
• Kept changes minimal and scoped only to leak points.

Why This Fix

Using stable function references allows window.removeEventListener(...) on unmount, preventing stacked listeners, memory leaks, and scroll-jank over long sessions.

Validation

• Manual code audit of scroll/resize listeners across src/**.
• No functional behavior change intended; only lifecycle cleanup.
• Tests were not run in this environment (per local workflow).

[rishiraj38]

LGTM!