v0.31.1 — make-skill

Correction to v0.31.0's MS-05 entry. That entry said the check refuses a temp-dir call
"through any receiver". Measured against temp_maker_hit(): it catches a direct call through
one receiver or none (tempfile.mkdtemp(, tf.mkdtemp(, mkdtemp() and a one-line renaming
from-import (from tempfile import mkdtemp as m); only whole-line # comments and """
blocks are skipped (chained receivers, function references, getattr and parenthesised
multi-line imports are not seen). A trailing # comment or a ''' block that names a
maker is read as code and refused, which errs toward a false refusal, not a miss.
The missing-back-link message says how the routing runs. test/validate.py told an
author that "the adapter skills route authors here and this skill must route them back";
only creating-fabric-agents routes here. The message now reads no back-link to <name> —
creating-fabric-agents routes packaging here; this skill names all three builders and
handling-secrets in return, and an in-gate self-test refuses the old wording.
HANDOFF records v0.31.0 as published (tag, release run, npm, hub pin) and keeps W4-C as
the single next task.