ureq over rustls (ring) with the OS certificate verifier. The project key
is the build-time FIELDCRAFT_POSTHOG_KEY; without it nothing is asked or
sent. FIELDCRAFT_TELEMETRY=0 turns it off; --control and CI runs only with
FIELDCRAFT_TELEMETRY=1. A failed post drops its batch.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
