harness: a standing advisory is a defect

The %w advisory counted every fmt.Errorf without %w, including calls that create
an error rather than wrap one — so it fired permanently on correct code. It now
looks for a call that passes an err and drops the %w, which is the actual rule.

Recorded the general form in the loop's Verify step and in HARNESS.md: a warning
that fires on correct code and keeps firing is a defect in the check or the code,
resolved in that change. Two advisories have now been narrowed after firing on
code the harness itself mandates, and the count creeping from one to two was the
only signal either time.

verify.sh is at zero warnings, which is what makes the next one legible.

scripts/verify.sh

@@ -377,7 +377,9 @@ panics=$(echo "$gofiles" | grep -v '_test\.go$' | grep -v '^\./cmd/' | xargs gre
 if [ -n "$panics" ]; then bad "panic() outside cmd/ — request-time failure degrades (conventions.md): $(echo "$panics" | tr '\n' ' ')"; else pass "no panic outside cmd"; fi
 
 head_ "smells (advisory)"
-nowrap=$(echo "$gofiles" | xargs grep -n 'fmt\.Errorf(' 2>/dev/null | grep -v '%w' | wc -l | tr -d ' ')
+# Only calls that actually wrap: fmt.Errorf without an err argument is creating an error, not losing one.
+nowrap=$(echo "$gofiles" | xargs grep -hn 'fmt\.Errorf(' 2>/dev/null |
+  grep -v '%w' | grep -cE '\berr\b' || true)
 [ "${nowrap:-0}" -gt 0 ] && note "$nowrap fmt.Errorf without %w (wrap at package boundaries)"
 # Only exported signatures: conventions.md bans interface{} as an API escape hatch, but ADR-0002 mandates
 # an open page object, so unexported code reading Extra legitimately takes any and always will.