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>

.gitea/workflows/ci.yaml

@@ -282,7 +282,7 @@ jobs:
       # avoid the file: almost every survivor is in akbasic_audio_state_init,
       # where nothing asserts that a freshly initialised audio state is actually
       # zeroed and defaulted -- the same gap this job's own history records
-      # closing for src/symtab.c. Recorded in TODO.md; add the file back when it
+      # closing for src/symtab.c. That is issue #25; add the file back when it
       # is closed.
       #
       # It was 73.1% before writing this job. The run's own findings closed the
@@ -297,7 +297,7 @@ jobs:
       #
       # The 21 remaining survivors are listed in the published report. Most are
       # ICR mutants on loop and accumulator initialisers that a stronger
-      # placement assertion would catch. Recorded in TODO.md.
+      # placement assertion would catch. Issue #25.
       - name: mutation testing
         run: |
           python3 scripts/mutation_test.py \