feat: install and update bat like the other tools

[YASoftwareDev]

What

bat is now installed, updated and tested like every comparable tool. It was
absent from this repo entirely - not in the apt list, not in _KNOWN_TOOLS, no
installer, no test, and referenced nowhere - while rg, fd, jq, zoxide, delta, eza
and yazi were all managed. Hosts that wanted it were fixed by hand.

The trap this shares with fd

The Debian/Ubuntu package is called bat but installs the binary as batcat
(the name was already taken). So has bat is false after a successful apt install,
and an installer that only checks bat would refetch it forever, while an
installer that treats batcat as "installed" would leave no bat on PATH at all.

fd/fdfind has exactly this shape and the repo already solved it, so this
follows that precedent: both names count as present, and a shim is created in
both install_base and install_base_docker.

The docker branch needs the shim even though its apt list does not ask for bat - a
base image may already carry batcat, and then _install_bat self-skips and that
path ends with no bat. That is a bug this PR would have introduced without it.

Also here: tmux joins the strict no-sudo check

1.12.0 added the no-sudo tmux installer but test.sh only checked tmux generically.
It is now checked strictly in ~/.local/bin alongside the other no-sudo binaries.

check_local_bin takes a version flag for this, because tmux --version prints its
usage rather than a version - it would have been reported as the version string.

Verified

bash ci-local.sh --ubuntu 24.04 --profile minimal --skip-nosudo - PASS 1/1, apt
path. The shim fired:

/root/.local/bin/bat -> /usr/bin/batcat

bash ci-local.sh --ubuntu 24.04 --profile nosudo-auto - PASS 1/1, GitHub path:

✓  bat   →  /home/user/.local/bin/bat   (bat 0.26.1 (979ba22))
✓  tmux  →  /home/user/.local/bin/tmux  (tmux 3.5a)

(and the -V flag renders tmux 3.5a, not the usage text.)

Red-proofs, both on the built image:

mutation	result
rm ~/.local/bin/bat	test_rc=1, bat / batcat not found + bat not found in ~/.local/bin
rm ~/.local/bin/tmux	test_rc=1, 3 findings

bash test.sh workstation 62/63, 0 failures, 1 skip. shellcheck clean (the SC2088
warnings it prints are pre-existing, on lines this PR does not touch).

A measurement note

While checking the shim I first read command -v bat inside bash -lc in the
image, saw nothing, and briefly concluded the shim had not fired. It had - the file
was there; ~/.local/bin simply is not on PATH in that shell, because .zshrc sets
it and test.sh exports it explicitly. Checking the file rather than command -v
is the reliable form, and this is the second time that context has misled me in this
work.