Enhanced HKDF-based key derivation with improved security features

- Implemented proper RFC 5869 compliant HKDF key derivation process
- Added Perfect Forward Secrecy (PFS) key for enhanced session security
- Improved key separation using unique info parameters for each derived key
- Enhanced salt size from 32 to 64 bytes for increased entropy
- Added comprehensive key validation and error handling
- Implemented proper ECDH + HKDF integration following Web Crypto API best practices
- Added metadata encryption key for enhanced data protection
- Improved compatibility with modern cryptographic standards (RFC 7748, NIST SP 800-56A)
 -Enhanced logging and debugging capabilities for cryptographic operations
- Maintained backward compatibility while upgrading security infrastructure
Security improvements:
- Cryptographic isolation between different key purposes
- Enhanced protection against cross-key attacks
- Improved resistance to future key compromise scenarios
- Better compliance with OWASP cryptographic storage guidelines
Technical details:
- Refactored deriveSharedKeys() method for proper HKDF implementation
- Updated WebRTC manager to use new messageKey API
- Added comprehensive error handling and validation
- Improved browser compatibility with standardized cryptographic operations
- This update strengthens the existing security foundation with modern cryptographic practices while maintaining full system compatibility.

src/app.jsx

@@ -1924,7 +1924,7 @@
                             }
                         }
         
-                        handleMessage(' SecureBit.chat Enhanced Security Edition v4.4.18 - ECDH + DTLS + SAS initialized. Ready to establish a secure connection with ECDH key exchange, DTLS fingerprint verification, and SAS authentication to prevent MITM attacks.', 'system');
+                        handleMessage(' SecureBit.chat Enhanced Security Edition v4.4.99 - ECDH + DTLS + SAS initialized. Ready to establish a secure connection with ECDH key exchange, DTLS fingerprint verification, and SAS authentication to prevent MITM attacks.', 'system');
         
                         const handleBeforeUnload = (event) => {
                             if (event.type === 'beforeunload' && !isTabSwitching) {