Overlay Playground Node DNS resolution for URL-import runtimes

## Problem

WP Codebox 0.18.4 ships Playground 3.1.46, whose Node PHP.wasm `dns_get_record()` returns an empty array. Public URL importers that validate resolved addresses, including Static Site Importer, fall back to synthetic loopback resolution and correctly reject the target as private. This prevents unchanged end-to-end URL intake in disposable Codebox runtimes.

## Proposed fix

Temporarily overlay the rebuilt Node PHP.wasm packages from WordPress Playground PR #4172 until an upstream Playground release contains the fix. Record the exact upstream commit and add a runtime proof that public A/AAAA records resolve without weakening importer SSRF checks.

Upstream: https://github.com/WordPress/wordpress-playground/pull/4172

## Acceptance criteria

- `dns_get_record()` returns real public records in the Node runtime.
- SSI runs its unchanged fetch, SSRF validation, collection, and import pipeline in WP Codebox.
- The temporary overlay is provenance-documented and removable after the upstream package release.

## AI assistance

OpenAI gpt-5.6-sol via OpenCode was used to reproduce the runtime incompatibility, identify the existing upstream Playground repair, and draft this tracker. Chris Huber remains responsible for the issue and resulting changes.

Inizia dal runtime Node di WP Codebox e dal suo punto di ingresso per l’acquisizione degli URL di Static Site Importer, quindi confronta i pacchetti Node PHP.wasm ricostruiti di WordPress Playground PR #4172 con gli attuali pacchetti Playground 3.1.46. Verifica che dns_get_record() restituisca record A/AAAA pubblici e che la pipeline invariata di fetch SSI, validazione SSRF, raccolta e importazione continui ad avere esito positivo, documentando il commit dell’overlay per la successiva rimozione.

Scritto dal modello di indicizzazione a partire dal testo della issue.