Plugins screen revamped; migration flows added

# Codex app ### New features - Added [Migrate to Codex](/codex/migrate) flows for importing supported setup from Claude Code and Claude Cowork, including during onboarding. - Revamped plugins screen with separate tabs, marketplace and category filters, keyboard navigation, and clearer install actions. - Expanded Settings search to find options from more panels, including Git and pets. ### Performance improvements and bug fixes - Fixed goal timer overlap in narrow layouts. - Reduced unread notifications while an active goal continues running. - Kept review diff ordering consistent with the file tree. - Improved window rendering on systems that don't support translucent backdrops, including Windows 10. - Additional performance improvements and bug fixes.