docs(comments): D-522 drain 5 — vm.zig de-pointering (92→10 ref lines)

Smell-audited: 1: comment-only pass per the established method (subagent,
zig build test + lint verified); 9 kept anchors are genuine design-citation
records, 4 stale comments fixed to code-truth (incl. the retired rt-ns
auto-refer claim and a "single-frame dispatcher" claim stale since
flattened frames).

Author: chaploud

.dev/debt.yaml

@@ -127,8 +127,16 @@ active:
       and 6 genuine comment anchors (ADR-0036 parity contract,
       ADR-0130 intrinsic cache, ADR-0038 forward refs, ADR-0060 ex_info
       class names, ADR-0047 peephole, ADR-0056 dispatch knot); comment
-      POINTER density in the file is drained. Next candidates by
-      density: vm.zig 89, print.zig 88.
+      POINTER density in the file is drained.
+      DRAIN 5 (2026-07-17): src/eval/backend/vm.zig 92→10 (9 genuine
+      anchors: ADR-0022 parity contract, ADR-0131 arena/frames,
+      ADR-0157 stack guard, ADR-0071 cleanup-unwind, ADR-0060 error
+      conversion, ADR-0118 loc propagation, ADR-0130 intrinsic deopt,
+      ADR-0050 member resolver, ADR-0056 dispatch knot; +1 test name).
+      4 stale comments fixed to code-truth (single-frame claim,
+      threadlocal-binding "stopgap" framing, rt-ns auto-refer, fragile
+      line-number pointers). PERF/GC-ROOT marker refs kept (mandatory
+      per their rules). Next candidate by density: print.zig 88.
     category: "docs"
     quality_floor: "public-ization: comment de-pointer + condense (ADR-0166)"
     barrier: |-