Add i18n support for session creation messages and ensure pending session names are properly set. Includes:
- Added MsgNewSessionCreated and MsgNewSessionCreatedName i18n messages
- Modified cmdNew to use i18n messages and handle empty names
- Set session name from pendingName in processInteractiveEvents if valid
generated by llmgit
Co-Authored-By: Claude <noreply@anthropic.com>