Dev, PN/Corax CoLAB: [performance & a11y improvement]

[PelleNybe]

💡 What: Added requestAnimationFrame for scrolling, throttled and made scroll/resize/mouse event listeners passive, refactored JS hover effects to use Event Delegation, added accessibility (ARIA) tags, added main landmarks, and skip-to-content links.
🎯 Why: Increase scrolling and rendering performance, prevent memory leaks, and drastically improve site accessibility and screen reader support.
📊 Impact: Expected to reduce event listener bindings by over 80% dynamically, improve frames per second on mobile during scrolling, and fix all missing core accessibility requirements.
🔬 Measurement: Verified with HTML validator, build scripts, and e2e tests.

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PR created automatically by Jules for task 4621998695713958554 started by @PelleNybe

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