fix(stormkit): properly send buffer responses

[pi0]

🔗 Linked issue

❓ 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

Stormkit requires buffer responses to be stringified AND be sent via buffer field instead of body.

This PR also updates types to match the underlying struct and normalized header.

Happy deployment: https://nuxt-image-remote-ipx.stormkit.dev/

📝 Checklist

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

[codecov]

Codecov Report

Merging #1616 (5ee3292) into main (6cb72e6) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1616   +/-   ##
=======================================
  Coverage   77.79%   77.79%           
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  Files          76       76           
  Lines        7835     7835           
  Branches      804      804           
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  Hits         6095     6095           
  Misses       1738     1738           
  Partials        2        2