Outbound Heartbeat

Post the daily outbound heartbeat to #sales-signals.

once_per_day=true (sent by both schedulers — the Railway cron-scheduler primary and the GitHub backup) makes the post idempotent per UTC day: the first caller atomically claims today's date in feature_flags and posts; later callers get 200 with skipped="already_posted_today". A failed Slack post releases the claim so the other scheduler can retry.

Driven once a day by .github/workflows/outbound-heartbeat-cron.yml. Leads created / enrolled / replied, positive intents, queue size and the state of every send gate — with a :rotating_light: line for a zero-enrolled day or any gate that is off. See outbound_heartbeat_service for why a heartbeat and not another alert.

AUTHED with X-Cron-Token: the response carries per-source lead counts and the gate configuration, and an anonymous caller could spam the sales channel. dry_run=true returns the rendered message without posting it. A real run whose Slack post fails returns 502 (body still carries the rendered text) so the cron job fails loudly.