Adds a webhook-level check so only members of $PUBLIC_REPO_ORG_GATE
(e.g. langchain-ai) can trigger Open SWE via mentions or review
requests on public repositories. Private repos remain governed by the
existing org/repo allowlists. Internal bots bypass the gate.
Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>
Co-authored-by: Johannes du Plessis <51395795+johannes117@users.noreply.github.com>
