Install the build dependencies CI has been missing since run #2

Every job in ci.yaml has failed on every run since #2, on main and on
every branch, for two reasons that have nothing to do with any of the
code under test.

moreutils, for errno(1). deps/libakerror/scripts/generrno.sh shells out
to it to generate its errno name table and to stamp
AKERR_LAST_ERRNO_VALUE into the generated akerror.h. The runner does not
have it, and its absence does not fail the build -- which is what made
this expensive to find. The script prints "errno: command not found",
emits an empty akerr_init_errno() so no errno ever gets a name, and
substitutes an empty AKERR_LAST_ERRNO_VALUE, so every code in
libakerror's reserved band collapses from (134 + n) to ( + n), i.e. to n.
AKERR_OUTOFBOUNDS is (AKERR_LAST_ERRNO_VALUE + 2) and therefore becomes
literally 2, so ERR(2) answers "Out Of Bounds Error" where ENOENT's "No
such file or directory" belongs. That is the docs_examples failure at
docs/15-error-codes.md:105, and it took cmake_build, sanitizers and
coverage down with it; mutation_test then aborted on "baseline is not
green" because the same suite is its baseline.

Reproduced locally by shimming errno(1) out of PATH: identical failure,
same test #47, same two lines of diff. With errno present the suite is
112/112.

The nine X11 dev packages, for akgl_build, which has never once been
green. SDL_X11 and its sub-options default ON on Linux, and CheckX11()
calls SDL_missing_dependency() -- a hard CMake error, not a downgrade --
for any whose header is absent. The runner has libx11-dev but none of
the extension packages, so configuration stopped at the first of them:
"Couldn't find dependency package for XCURSOR". The list is SDL's own,
from deps/SDL/docs/README-linux.md, reduced to the X11 entries; the
audio, Wayland, KMSDRM and Vulkan backends all degrade to "not found"
and skip themselves rather than erroring, so they cost nothing to leave
out. Turning the missing options OFF would also configure and is the
wrong answer -- the point of that job is that an AKGL build is a real
SDL program. The tests still run headless under SDL_VIDEODRIVER=dummy.

release.yaml's full_mutation job builds the same tree and gets moreutils
for the same reason.

No source file changes. The port itself was never the problem.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitea/workflows/release.yaml

@@ -70,10 +70,14 @@ jobs:
           # corpus is part of what kills mutants and it is checked in now, so
           # that is libakerror and libakstdlib and nothing else.
           submodules: true
+      # moreutils for errno(1), which deps/libakerror's scripts/generrno.sh needs
+      # to generate its errno table. Without it the generated table is empty and
+      # every AKERR_* code collapses onto a low integer -- see the long note on
+      # ci.yaml's cmake_build job for what that breaks and how it presents.
       - name: dependencies
         run: |
           sudo apt-get update -y
-          sudo apt-get install -y cmake gcc python3
+          sudo apt-get install -y cmake gcc python3 moreutils
       # The whole akbasic-owned src/ tree. ci.yaml runs a two-file subset on every
       # push; this is the one that actually covers the interpreter.
       #