terminal: Add bash shell indicator to starship prompt

So we know that we are not in a zsh shell currently.

terminal/.config/starship.toml

@@ -3,12 +3,13 @@
 
 format = """
 $sudo\
+$custom\
 $username\
 $directory\
 $git_state\
 $git_status\
 $status\
-$character
+$character\
 """
 
 right_format ="""
@@ -80,6 +81,10 @@ symbol = " 󱍔 "
 style = 'bold yellow'
 format = "[$symbol]($style)"
 
+[custom.shell_bash_indicator]
+command = 'echo 󱆃'
+when = ''' test "$0" = "/usr/bin/bash" '''
+
 # TODO: Would be lovely to have jujutsu support here
 # An example implementation: https://github.com/jj-vcs/jj/wiki/Starship
 # But currently very slow. Can be added with e.g. '${custom.jj}\' in format above