chore(nextjs): Update middleware check for proxy usage

[alexcarpenter]

Description

Checklist

• [ ] pnpm test runs as expected.
• [ ] pnpm build runs as expected.
• [ ] (If applicable) JSDoc comments have been added or updated for any package exports
• [ ] (If applicable) Documentation has been updated

Type of change

• [ ] 🐛 Bug fix
• [ ] 🌟 New feature
• [ ] 🔨 Breaking change
• [ ] 📖 Refactoring / dependency upgrade / documentation
• [ ] other:

Summary by CodeRabbit

• New Features

  • Added automatic detection and support for Next.js 16+ projects.

• Improvements

  • Guidance and onboarding messages for middleware/proxy configuration now adapt to your Next.js version, offering version-appropriate file location suggestions.

• Chores

  • Release metadata updated to include this patch.

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