Send Message API

Requires authenticated session (Clerk). Supports:

// Text (default)
{ "to": "27821234567", "phoneNumberId": "...", "text": "Hello" }

// Image
{ "type": "image", "to": "...", "phoneNumberId": "...", "mediaUrl": "https://...", "caption": "..." }

// Template
{ "type": "template", "to": "...", "phoneNumberId": "...", "templateName": "welcome_utility", "language": "en", "components": [...] }

// CTA URL button (tappable link)
{ "type": "cta_url", "to": "...", "phoneNumberId": "...", "bodyText": "View your quote", "buttonText": "Open link", "url": "https://...", "footerText": "..." }