When agents send replies from the native Facebook Messenger app (not Chatwoot), echo events were created without external_echo metadata and could be misrepresented in the UI. This change updates Messenger echo message creation to: - set content_attributes.external_echo = true for outgoing_echo messages - set echo message status to delivered - keep sender as nil for echo messages (existing behavior) <img width="2614" height="1264" alt="CleanShot 2026-02-26 at 16 32 04@2x" src="https://github.com/user-attachments/assets/ba61c941-465d-4893-814e-855e6b6c79e8" />