CVE-2026-32231: ZeptoClaw: Generic webhook channel trusts caller-supplied identity fields; allowlist is checked against untrusted payload data

The generic webhook channel trusts caller-supplied identity fields (sender, chat_id) from the request body and applies authorization checks to those untrusted values. Because authentication is optional and defaults to disabled (auth_token: None), an attacker who can reach POST /webhook can spoof an allowlisted sender and choose arbitrary chat_id values, enabling high-risk message spoofing and potential IDOR-style session/chat routing abuse.