fix: resolve turbopack regression

[stipsan]

The fix for Nuxt (#625) broke Next with Turbopack again (#606).

The last reproduction was a false positive..
The Turbopack issue happens whenever a client component imports an @sanity/client instance.

next dev --turbo
   ▲ Next.js 14.1.3 (turbo)
   - Local:        http://localhost:3000

 ✓ Ready in 886ms
 ○ Compiling / ...
 ✓ Compiled / in 5.1s

 ⨯ app/sanity.ts (3:13) @ <unknown>
 ⨯ TypeError: __TURBOPACK__imported__module__$5b$project$5d2f$node_modules$2f$next$2d$sanity$2f$node_modules$2f40$sanity$2f$client$2f$dist$2f$index$2e$cjs$2e$js__$5b$app$2d$ssr$5d$__$28$ecmascript$29$__.createClient is not a function
    at /workspace/.next/server/chunks/app_7485fc._.js:12:220
    at [project]/app/sanity.ts [app-ssr] (ecmascript) (/workspace/.next/server/chunks/app_7485fc._.js:19:3)
    at instantiateModule (/workspace/.next/server/chunks/[turbopack]_runtime.js:488:23)
    at getOrInstantiateModuleFromParent (/workspace/.next/server/chunks/[turbopack]_runtime.js:539:12)
    at esmImport (/workspace/.next/server/chunks/[turbopack]_runtime.js:113:20)
    at /workspace/.next/server/chunks/app_7485fc._.js:29:117
    at [project]/app/page.client.tsx [app-ssr] (ecmascript) (/workspace/.next/server/chunks/app_7485fc._.js:56:3)
    at instantiateModule (/workspace/.next/server/chunks/[turbopack]_runtime.js:488:23)
    at getOrInstantiateModuleFromParent (/workspace/.next/server/chunks/[turbopack]_runtime.js:539:12)
    at commonJsRequire (/workspace/.next/server/chunks/[turbopack]_runtime.js:127:20)
  1 | import { createClient } from "next-sanity";
  2 |
> 3 | export const client = createClient({
    |             ^
  4 |   projectId: "hiomol4a",
  5 |   dataset: "development",
  6 |   apiVersion: "2024-03-07",

The fix is to remove the node.import re-export wrapper pattern completely. Testing a canary of this PR solves the repro..
It doesn't cause regressions in Node runtimes. Moving forward it seems we need to end the Dual Package Hazard patterns for compatibility with the npm ecosystem of frameworks and runtimes.