feat: add `nuxt-whatsapp-widget`

[oussamalkd]

🔗 Linked issue

❓ Type of change

• [ ] 📖 Documentation (updates to the documentation or readme)
• [ ] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [ ] 👌 Enhancement (improving an existing functionality)
• [x] ✨ New feature (a non-breaking change that adds functionality)
• [ ] 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This PR adds the nuxt-whatsapp-widget module to the Nuxt Modules directory.

nuxt-whatsapp-widget is a floating WhatsApp chat widget for Nuxt 3. It allows developers to easily integrate a support or sales chat button into their Nuxt apps with minimal setup.

✨ Features Fully configurable via nuxt.config.ts or component props

Custom agent name, image, and welcome messages

Auto-injected widget, with optional manual use

Supports string or array messages

Lightweight and styled for minimal footprint