fix(verify): attach stdin (-i) so the zaak-status read-back runs (refs #106)

The cancellation reaches OpenZaak correctly (Geannuleerd status_created), but
the verify read-back ran 'docker run python:3-slim python -' without -i, so the
heredoc never reached the container's stdin and the script was empty — the check
always saw an empty status. Add -i so the read actually queries OpenZaak.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

infra/run-domain-check.sh

@@ -364,7 +364,8 @@ zaak_url_v="$(printf '%s' "$body" | grep -oiE 'http://[^"]*/zaken/api/v1/zaken/[
 echo ">> confirming the zaak $zaak_url_v reached the Geannuleerd status in OpenZaak"
 
 read_zaak_status() {
-  docker run --rm --network "$net" \
+  # -i so the heredoc reaches `python -` on the container's stdin (without it the script is empty).
+  docker run --rm -i --network "$net" \
     -e OZ_CLIENT_ID="${OZ_CLIENT_ID:-big-reference-seed}" \
     -e OZ_SECRET="${OZ_SECRET:-insecure-dev-secret-change-me}" \
     python:3-slim python - "$1" <<'PY'