#778 Demo/research tenant Gmail token stale -> send fails ('Gmail token refresh failed'); offer SMTP fallback for agent email

run_goal research+email path works end-to-end (HITL approval + dispatch) but apps.platform.gmail.send_email errored with 'Gmail token refresh failed' for tenant demo (OAuth token expired). Not a code bug. Mitigations: connect_gmail to refresh; or steer the agent to tools.email.send (SMTP, configured mail.highway.rodmena.app) when Gmail is not connected, so emailed reports degrade gracefully.