Append a new content block to a link-in-bio page. The block must match one of the 13 allowed types (link, social_row, whatsapp, phone_call, email_contact, image, gallery, video_embed, text, map_embed, product_card, lead_form, reviews) with that type's strict props. The server generates the block id and returns it in the response. For already-published pages, this saves an unpublished latest revision only. Do not call page.publish in the same assistant turn after this edit. Stop and tell the user the draft/preview was updated, then wait for a separate user message that explicitly asks to update the live link, publish, or make the changes public before calling page.publish. Do NOT call page.unpublish either — the live page should stay public; only unpublish when the user explicitly asks to take it down. The response includes nextSteps: after adding a block, share these hints with the user so they know what else would make the page more complete.