get_search_config returned SEARCH_CONFIG.copy(), and update_search_config
cached the decrypted Brave key into that shared global at startup
(app_initializer), so the unauthenticated /api/search/config route exposed
the operator's key. The cache was dead weight: brave_search reads its key
via _get_provider_key (settings/env), never SEARCH_CONFIG.
- update_search_config: no longer stores the api_key in the shared global
(accepted for backward compat; provider keys are read on demand).
- get_search_config: scrub any string-valued credential field before
returning, preserving the has_api_key presence flag.
No schema change; brave_search/_get_provider_key untouched. Adds regression
tests.
Fixes#1661
Co-authored-by: Ethan <23321960+0xLeathery@users.noreply.github.com>