fix(blob): use variable for vercel-blob dynamic import

[onmax]

Closes #809

Summary

useMultipartUpload fails with fs driver because Vite statically analyzes import('@vercel/blob/client') at dev time. Fix uses variable indirection so Vite's es-module-lexer can't extract the specifier.

StackBlitz

	Link	Expected
Bug	nuxthub-809	❌ Dev fails
Fix	nuxthub-809-fix	✅ Dev works

CLI Reproduction

git clone --depth 1 --filter=blob:none --sparse https://github.com/onmax/repros.git
cd repros && git sparse-checkout set nuxthub-809
cd nuxthub-809 && pnpm i && pnpm dev

Verify fix

git sparse-checkout add nuxthub-809-fix
cd ../nuxthub-809-fix && pnpm i && pnpm dev

The -fix folder uses pnpm patch to apply the fix locally.

[vercel]

@onmax is attempting to deploy a commit to the NuxtLabs Team on Vercel.

A member of the Team first needs to authorize it.

[pkg-pr-new]

npm i https://pkg.pr.new/@nuxthub/core@810

commit: bbd338c

[alexcroox]

@atinux we are still unable to implement handleMultipartUpload with Cloudflare because of this. Could we get it merged?

[atinux]

Thank you for the ping @alexcroox, missed it!

But you could use the pkr.pr release in the meantime

[alexcroox]

Thank you <3

[alexcroox]

I'm afraid this still didn't fix the issue. I've created a new issue and included a simple repro #859