perf(netlify-legacy): exclude static paths from server handler

[serhalp]

🔗 Linked issue

N/A - discussed on Discord

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ 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

Follow-up to #2822 — backporting the same fix to netlify-legacy.

Since it's using "v1" Netlify Functions (https://docs.netlify.com/functions/lambda-compatibility), it doesn't have access to excludedPath and preferStatic, so we implement this with redirects. See the inline comment.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[serhalp]

@pi0 and here's the backport for netlify-legacy

Here's a manual QA against a nuxt site (nuxt v3, default compat date, i.e. using legacy preset):

• site homepage is rendered via SSR: https://672399ade8c61420b080bcf8--nuxt-test-static-assets-fix.netlify.app
• a nonexistent path under /_nuxt returns a 404 directly from the CDN without invoking a function: https://672399ade8c61420b080bcf8--nuxt-test-static-assets-fix.netlify.app/_nuxt/fake-old-file-123.css
• a real path under /_nuxt returns a 200 directly from the CDN without invoking a function: https://672399ade8c61420b080bcf8--nuxt-test-static-assets-fix.netlify.app/_nuxt/entry.CQDx9R-V.css

[pi0]

Thank you!