feat: rebrand to SecureBit.chat due to name conflict

BREAKING CHANGE: Project renamed from LockBit.chat to SecureBit.chat

- Changed project name to avoid confusion with LockBit ransomware group
- Updated all documentation, branding, and references
- Maintained all existing functionality and security features
- Domain migration planned to securebit.chat

Reason: The LockBit name became associated with a notorious ransomware
group, causing conflicts on platforms and potential confusion for users.
SecureBit better reflects our mission of providing secure P2P messaging
while avoiding negative associations.

This change affects:
- README.md and all documentation
- Package.json name field
- Brand assets and logos
- Website references
- Social media handles

Core functionality remains unchanged:
✅ 12-layer military-grade security
✅ Lightning Network integration
✅ P2P WebRTC architecture
✅ Open source MIT license

src/crypto/EnhancedSecureCryptoUtils.js

@@ -1275,7 +1275,7 @@ class EnhancedSecureCryptoUtils {
             const encoder = new TextEncoder();
             
             // Enhanced context info with version and additional entropy
-            const contextInfo = encoder.encode('LockBit.chat v4.0 Enhanced Security Edition');
+            const contextInfo = encoder.encode('SecureBit.chat v4.0 Enhanced Security Edition');
             
             // Derive master shared secret with enhanced parameters
             // Try SHA-384 first, fallback to SHA-256