fix(dev): restart nuxt if unhandled rejection occurs

[danielroe]

🔗 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)
• ✨ 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

investigating nuxt/nuxt#30137 (comment), every time I started Nuxt, a zombie process would be left behind due to an unhandled rejection.

this adds handling to kill + restart nuxt, which doesn't address the issue (still investigating - it's about watchers) but at least prevents zombie processes from accumulating

(alternatively, or perhaps in future, we could add an additional signal if we wanted to handle differently - would love ideas @pi0)