Add next-intl JSON HMR regression test for #91768
Tests JSON HMR with next-intl's getRequestConfig pattern that uses dynamic
import() with template literals to load locale messages. Covers both server
components (getTranslations) and client components (useTranslations), patching
messages/en.json multiple times to catch the "second edit ignored" regression.
Co-Authored-By: Claude <noreply@anthropic.com>
