1.3.1

1.3.1: faster on slower computers

- Streaming answers draw only the part that changed, and code colors are
  worked out once: a long answer no longer slows the window down as it
  grows.
- The sub-agents panel updates the paragraph being written instead of
  redrawing everything, and a sub-agent writing no longer redraws its row
  in the conversation.
- The browser pane does no work while nothing moves around it.
- The run journal keeps the copies of changed files beside it, so each
  step of a tool call writes a few kilobytes instead of every file again.
  Older journals are read and converted on their next write.
- Settings reopens on its last tab; one account button in the sidebar.