The terminal JS uses GET with a free-text ?q= parameter, but only a POST
endpoint existed with typed params (card_id, qr_code, card_number).
- Add search_card_for_store service method (tries card number then email)
- Add GET /cards/lookup route using the service method
- Extract _build_card_lookup_response helper to DRY up POST and GET endpoints
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>