The NPSSO is used once to get a refresh token; only that token is
stored, sealed with AES-GCM (SecretBox, key APP_PSN_TOKEN_KEY; no key
= feature off). One-time import of played PS4/PS5 titles through the
import pipeline as source PSN. Unlink keeps the games. One PSN call
per user at a time. IGDB search now sends UTF-8, so non-ASCII names
like "Yōtei" match again.
