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>

include/akbasic/ui.h

@@ -57,7 +57,7 @@
  * These are akgl_UiAnchor's five values and its numbering, so the adaptor maps
  * them across without a table. **There is deliberately no top-centre or
  * bottom-centre**, because libakgl has neither and this repository does not edit
- * its dependencies to add one; see TODO.md.
+ * its dependencies to add one; see libakgl issues #79 and #80.
  */
 typedef enum
 {

include/akbasic/value.h

@@ -3,8 +3,8 @@
  * @brief Declares the strongly-typed BASIC value and its operators.
  *
  * Ported from the reference's basicvalue.go. The arithmetic is reproduced
- * exactly, including the parts that look wrong -- see TODO.md section 12 for the
- * catalogue and the reason they are not fixed yet.
+ * exactly, except where a defect has since been fixed on its own merits -- see
+ * TODO.md §6 for the catalogue and what became of each.
  *
  * **The left operand decides whether an operation is done in integers or in
  * floats**, and this is deliberate rather than an oversight: every operator