revert(shell): move iris integration to the iris branch

Reverts 43dfe48, 0692ae3, e0cdcd6 and the cable-description half of
098da70 (the star-prompt stats stay). master returns to the pre-iris
shell setup: atuin in fish/zsh/bash, the down -> pj binding with
PJ_QUIET, and the fish/zsh key bindings as they were. The iris work
lives on the `iris` branch.

docs/chezmoi/index.mdx

@@ -52,7 +52,6 @@ The repo is a [chezmoi](https://chezmoi.io) source directory. It lives at `~/.lo
   - herdr-nvim/
   - hunk/
   - hypr/
-  - iris/
   - kitty/
   - lazydocker/
   - lazygit/