Windows: use Cygwin bash, not Powershell

What feature would you like to see?

I start Codex from a Cygwin bash, and I'd like it to use that shell, not Powershell. This will in particular allow sharing permission rules with those used under WSL.

Btw, currently the rules are all like:

prefix_rule(pattern=["C:\\WINDOWS\\System32\\WindowsPowerShell\\v1.0\\powershell.exe", "-Command", "FULL COMMAND"], decision="allow")

which is pretty useless (the full command is just the 2nd argument to powershell -> no way to specify a useful "prefix" of the argument list)

Additional information

_No response_