Sends a WhatsApp template message

Sends a WhatsApp template message to a contact.

Use body_parameters to fill the template’s body variables ({{1}}, {{2}}, …). It is positional — the first element fills {{1}}, the second {{2}}, and so on — and each element must be { "type": "text", "text": "..." } (no name/value). The number of elements should match the number of variables in the template. For templates with media headers, use header_parameters with document/image/video links. For templates with URL buttons, use buttons_parameters to set the dynamic URL suffix. Use from_phone_number to choose which of the account’s WhatsApp numbers sends the message.