Why: passwordless activation/recovery must redeem only into a
set-password session; account ops must not create empty stores.
Evidence: SELF go test store/server login-key and OpenExisting cases.
Impact: auth middleware gates; CLI user create defaults to activate key.
Refs: docs/svc-deploy/u4-one-time-login-key.md
Co-authored-by: Cursor <cursoragent@cursor.com>