Sends a contact card.
SendDocument delivers a document message.
SendImage delivers image-specific messages.
Sends an interactive message (buttons, lists, CTA). Supports idempotency via send_id.
Handles user interaction callbacks. Should be called by client when user interacts with UI.
Sends a geographic location message.
SendText delivers a plain text message. We use the shared Request/Response types directly to avoid duplication.
Mark message as read by id.