The service now reads the optional MEALQUEST_SEARXNG_URL, validates it at
startup like any SearXNG URL, and returns it in the recipe search settings
as the read-only default_base_url. base_url stays the saved URL only, and
PATCH is unchanged: nothing is stored until the household saves.
The recipe search card pre-fills the SearXNG URL from default_base_url
while no URL is saved, and an edit now clears the last Test result so a
stale count or error never sits beside "Save your changes to test them."
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>