[Feature Request] Support standard terminal keyboard bindings (vi/emacs line editing)

Question

**Bug Description**
Claude should respect the standard keyboard bindings available in terminals, ie. vi and emacs. Currently ctrl-b is bound to a background job not the emacs cursor-left, and can't be overridden back to cursor-left.

Maintaining this behavior is part of being a good terminal application.

As Claude suggested when I tried to debug this, tmux already breaks that, but tmux offers rebindings, so the usual tmux ctrl-b trigger can be made to be whatever the user wants, if they want to