Repoint the TODO.md citations that no longer resolve

Its own SS0-SS9 structure survived the move to the tracker, so 133 citations
still resolve and are left alone. Thirteen did not.

Six named another repository's TODO.md by a section number: libakstdlib 1.6,
2.2.2 and 2.3, and libakgl's file. Those repositories dropped their numbering
entirely, so each now names UPGRADING.md, an issue, or the tracker.

Three cited 'TODO.md section 12', which has never existed here -- the defect
list is SS6. TODO.md itself caught two others of that class earlier. The
CMakeLists comment carried a stale premise with it: eleven defects
'deliberately reproduced and not yet fixed' stopped being the rule when SS0.1
retired the fidelity constraint.

Four told a reader to record work in TODO.md; the scanner defect is issue #4,
the audio_tables mutation gap is #25, and the UI gaps are libakgl #79 and #80.

Verified: cmake --build build && ctest --test-dir build, 112/112.

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

src/runtime_disk.c

@@ -389,7 +389,7 @@ akerr_ErrorContext *akbasic_cmd_directory(akbasic_Runtime *obj, akbasic_ASTLeaf
      * Refused rather than half-built. Listing a directory needs opendir/readdir,
      * which `libakstdlib` does not wrap -- and this project's rule is that a
      * missing capability gets filed upstream rather than worked around here
-     * (MAINTENANCE.md). Filed in deps/libakstdlib/TODO.md.
+     * (MAINTENANCE.md). Filed as libakstdlib issue #10.
      *
      * The alternative was shelling out to `ls`, which a library has no business
      * doing, or calling readdir directly and stepping outside the error