Add kd-screen-guard library to README

[KhvichaDev]

Hi! I'd like to propose adding kd-screen-guard to the React Libraries section.

kd-screen-guard is a standalone, zero-dependency, tamper-proof lock screen library built for web applications:

• Native React hook (useScreenGuard)
• WebAuthn Biometrics (Touch ID, Face ID, Windows Hello)
• WebRTC Intruder Snapshot capture
• Off-main-thread Web Worker PBKDF2 cryptography
• Self-healing Anti-Tamper DOM protection

GitHub: https://github.com/KhvichaDev/kd-screen-guard
NPM: https://www.npmjs.com/package/kd-screen-guard

Thank you for maintaining this awesome list!