use zmx for persistent sessions instead of tmux

[adrian-gierakowski]

https://github.com/neurosnap/zmx

tmux creates an unnecessary indirection and causes things to break in unexpected ways (see: https://bower.sh/you-might-not-need-tmux)

zmx uses libghostty-vt which is being adopted by many projects due to it's comprehensive support for modern terminal protocols, for example:

• https://github.com/robmorgan/agentd
• https://github.com/flotilla-org/cleat

[linear]

PCC-299