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.

television/cable/pj.toml

@@ -4,8 +4,8 @@ description = """
 Project tasks from every task source between the cwd and the git toplevel
 (package.json, Makefile, justfile, mise, devbox, pyproject), tasks of the most
 recently modified manifest first. Enter runs the task. Discovery, preview and
-run live in ~/.local/bin/pj; `pj` (ctrl-p in fish, zsh and bash) opens this
-cable with its own scan.
+run live in ~/.local/bin/pj; `pj` (ctrl-p, and down on an empty prompt in fish,
+zsh and bash) opens this cable with its own scan.
 """
 requirements = ["pj", "mtime-sort"]