Address Greptile review: externally-initiated outbound-api calls were
stored with hardcoded direction: "inbound". Now createWebhookCall accepts
a direction parameter so the CallRecord accurately reflects the event's
actual direction. Also skip inboundGreeting for outbound calls and add a
test asserting inbound direction is preserved.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>