fix(db): avoid reusing hyperdrive postgres client

[onmax]

Summary

Fix the Cloudflare Hyperdrive postgres-js path to cache the Drizzle client per request instead of reusing a module-global client across Worker requests.

Scope is intentionally narrow:

• only the Hyperdrive postgres-js branch changes
• cache on useEvent().context
• preserve current Hyperdrive option handling
• leave other drivers and branches unchanged

Related

• fix(auth): rebuild nuxthub adapters and server auth type refs nuxt-modules/better-auth#295 (comment)
• PR #844

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[pkg-pr-new]

npm i https://pkg.pr.new/@nuxthub/core@895

commit: 77505ad

[onmax]

This also reproduces in https://github.com/nimiq/crypto-map on the Cloudflare runtime.

We hit failing DB-backed requests there with the Hyperdrive + postgres-js path, so this fix is relevant for a real downstream app as well.