Provider credentials are bootstrap config and never reach the database
(DESIGN.md §10), so which providers exist is settled once at startup;
which of them a search runs is the `providers_enabled` row the API reads
per request. OpenSubtitles.com cannot be called without a registered API
key, so without one it is not offered at all.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Miguel Palhas
faa7a0c056