refs #1117
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## Summary by CodeRabbit
- **Refactor**
- Dynamically construct API URLs for WhatsApp features using environment
variables for improved reliability and configurability.
- Updated `sendWhatsAppMessage` function to use
`env.WHATSAPP_CLOUD_API_URL` for URL construction, allowing for more
dynamic configuration.
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Co-authored-by: Baptiste Arnaud <baptiste.arnaud95@gmail.com>
