No modal when I create a new terminal with `shellStartup`

[meganrogge]

Testing #340

If you don't have any terminals open then you will not see the modal until you create a terminal

I do not see a modal

existing.mov

[meganrogge]

I only saw this after creating a fish terminal, not pwsh nor zsh.

[eleanorjboyd]

given shell integration this now works differently (in that it only adjusts the shell script if no shell integration exists). I have tried it with this flow, and it now works so this should be resolved