Google sign-in: set NEXT_PUBLIC_AUTH_ENABLED=true, AUTH_SECRET, and AUTH_GOOGLE_ID / AUTH_GOOGLE_SECRET in .env.local. Restart npm run dev after changing NEXT_PUBLIC_* vars.
NEXT_PUBLIC_AUTH_ENABLED=true
AUTH_SECRET
AUTH_GOOGLE_ID
AUTH_GOOGLE_SECRET
.env.local
npm run dev
NEXT_PUBLIC_*