List email templates

Everything a SEND_EMAIL node needs: the PUBLISHED email templates it can use, the org's email readiness, and the senders available as From / Reply-To overrides. Email has no channelId — it sends from the org's verified domain — which is why it is not in journeys_message_channels. Publish refuses a SEND_EMAIL node unless readiness.verified and readiness.hasSender are both true (or the node sets a fromSenderIdOverride whose sender is usableAsFrom).