- Backend: return `configured` field alongside `running`. When
alive=None (no gateway metadata), configured=false with fallback to
identity_map heuristic.
- Frontend: amber "Gateway not configured" when configured=false,
red "Gateway not running" only when configured but process is down,
green "Running" when both true.
- Replace dead try/except fallback with explicit tri-state check on
health["alive"].
- Add regression test for last_active guard when alive=true and
identity_map is empty.
All 87 gateway-related tests pass.
Use agent_health.build_agent_health_payload() as the authoritative
running signal instead of bool(identity_map). An empty identity_map
means zero connected messaging platforms, not that the gateway is down.
Falls back to identity_map heuristic when agent_health module is unavailable
(e.g. WebUI-only deployments).
