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

test-lnbits-integration.html

@@ -158,7 +158,7 @@
                     body: JSON.stringify({
                         out: false,
                         amount: 500,
-                        memo: 'LockBit.chat test invoice',
+                        memo: 'SecureBit.chat test invoice',
                         unit: 'sat',
                         expiry: 300
                     })