Take libakerror 2.0.2, libakstdlib and libakgl 0.9.0

Bumps all three ak* submodules to their current main, applies what their
upgrade notes require, and retires the two workarounds they make obsolete.

libakerror 2.0.1 -> 2.0.2 (63 commits). Two of its fixes were this
repository's own filed issues, and both workarounds are gone:

  - It namespaces its embedded `coverage` target now, the same
    CMAKE_SOURCE_DIR test it already applied to `mutation` (its issue #15).
    The add_custom_target() shadow that renamed it on the way past could
    only ever fire on a name the dependency has stopped using, so it is
    deleted rather than left as dead code.
  - It installs akerrorConfigVersion.cmake at SameMajorVersion (its issue
    #16). MAINTENANCE.md said to add a `1.0` floor to our find_dependency
    calls when this landed; the floor is now `2.0`, and we have no
    find_dependency calls to add it to, so the paragraph says that instead
    of an instruction nobody can follow.

Its IGNORE context also changed shape: `__akerr_last_ignored` was an extern
pointer, and is now a per-translation-unit `static akerr_last_ignored` holding
a copy, so the pool slot can be released. Nothing here referenced the symbol,
but it costs us 1.35 MiB of thread-local storage -- 38 TUs x 37,296 bytes,
measured as the entire TLS segment of build/basic, where 2.0.1 produced no TLS
segment at all -- plus 84 -Wunused-variable warnings. Filed upstream as
libakerror issue #37 and recorded in MAINTENANCE.md rather than patched here,
because patching a submodule forks it.

libakstdlib gains directory and file-metadata wrappers with no version bump.
aksl_snprintf keeps its `int *count` -- an intermediate commit removed it and
the merge put it back -- but now reports the required length on truncation
rather than 0. Every call site here reads it only after a successful return,
so nothing moved.

The directory wrappers close the gap DIRECTORY was refused for (libakstdlib
issue #10). The verb is still unwritten, so it still refuses, but it no longer
blames a wrapper that exists: the message is "DIRECTORY is not implemented
yet" and tests/disk_verbs.c asserts both that it says so and that it does not
name libakstdlib. What writing it would need is akbasic issue #55.

libakgl moves to the current main at 0.9.0. It registers libccd and tg as
submodules, so a tree that only ran `git submodule update --init --recursive`
before the bump needs it again or the configure fails on a missing
libccd/src/ccd/config.h.cmake.in.

Verified: 114/114 default, 116/116 under -DAKBASIC_WITH_AKGL=ON, docs_examples
green in both. libakerror's UPGRADING.md documents a 2.0.3 that project()
never stamped, so the version tables read 2.0.2 -- libakerror issue #38.

Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
Co-Authored-By: Claude Code (Claude Opus 5, claude-opus-5[1m]) <noreply@anthropic.com>

include/akbasic/error.h

@@ -12,9 +12,12 @@
  * libakerror 2.0.0 is the floor, raised from 1.0.0 because 2.0.0 is an ABI break
  * that a compile against the wrong header cannot survive quietly:
  *
- *   - `__akerr_last_ignored` became thread-local. `IGNORE` expands at *our* call
- *     site, so our objects reference that symbol under whichever storage model
- *     the header on the include path declared.
+ *   - The context behind `IGNORE` became thread-local. `IGNORE` expands at *our*
+ *     call site, so our objects reference that storage under whichever model the
+ *     header on the include path declared. 2.0.2 went further and made it a
+ *     per-translation-unit `static` snapshot named `akerr_last_ignored`, copied
+ *     from the pool slot so the slot can be released; the old spelling
+ *     `__akerr_last_ignored` was an `extern` pointer and no longer exists.
  *   - `akerr_next_error()` now returns a context that already holds a reference,
  *     and `ENSURE_ERROR_READY` no longer increments. Objects compiled against a
  *     1.x header count every reference twice and never give a slot back.