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/components/ui/Header.jsx

@@ -105,7 +105,7 @@ const EnhancedMinimalHeader = ({
                         React.createElement('h1', {
                             key: 'title',
                             className: 'text-lg sm:text-xl font-semibold text-primary'
-                        }, 'LockBit.chat'),
+                        }, 'SecureBit.chat'),
                         React.createElement('p', {
                             key: 'subtitle',
                             className: 'text-xs sm:text-sm text-muted hidden sm:block'