redact: SendGrid prefix pattern masks only the key-id segment — the key-secret segment stays in cleartext

#58167 Workaround P2 comp/agent

redact: SendGrid prefix pattern masks only the key-id segment — the key-secret segment stays in cleartext

The SendGrid redaction regex in agent/redact.py stops matching at the second dot, so the key-secret segment of a 3-part SendGrid API key remains unmasked in cleartext in logs and transcripts.