Allow user to edit files with $EDITOR before saving

[mikery]

Related to #282 . When creating/editing a file the options are:

Do you want to make this edit to CLAUDE.md?                                                                                                                                                                                                    
  ❯ Yes                                                                                                                                                                                                                                       
  Yes, and don't ask again this session                                                                                                                                                                                                        
  No, and tell Claude what to do differently (esc)  

It would be great to have an option to open the file in $EDITOR before it is saved/edited.

[bcherny]

Why not say yes, then edit in $EDITOR?