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>

tests/disk_verbs.c

@@ -244,10 +244,16 @@ static void test_no_drive_verbs(void)
 	harness_stop();
     }
 
-    /* DIRECTORY is refused for a different reason, and says which. */
+    /*
+     * DIRECTORY is refused for a different reason than the five above: not for
+     * want of a drive, but because it is unwritten. It used to name the missing
+     * libakstdlib wrapper; that wrapper landed, so naming it would be a lie.
+     */
     TEST_REQUIRE_OK(run_program("10 DIRECTORY\n"));
-    TEST_REQUIRE(strstr(HARNESS_OUTPUT, "libakstdlib") != NULL,
-		 "DIRECTORY should name the missing wrapper, got \"%s\"", HARNESS_OUTPUT);
+    TEST_REQUIRE(strstr(HARNESS_OUTPUT, "not implemented") != NULL,
+		 "DIRECTORY should say it is unwritten, got \"%s\"", HARNESS_OUTPUT);
+    TEST_REQUIRE(strstr(HARNESS_OUTPUT, "libakstdlib") == NULL,
+		 "DIRECTORY must not still blame libakstdlib, got \"%s\"", HARNESS_OUTPUT);
     harness_stop();
 }