A hijacked session must not be able to silently add a passkey as a
persistent backdoor or remove the victim's credentials. Registration
(begin) and deletion now verify the account password server-side,
reusing the existing PASSWORD_REQUIRED / PASSWORD_INCORRECT errors.
The password is used instead of TOTP step-up so the guard also protects
deployments that never configured a TOTP encryption key. The password
key in both request bodies is covered by the audit middleware's
key-substring redaction, so no credential material reaches audit_logs.
Frontend: the add-passkey form gains a current-password field, and the
delete confirmation is now a dialog with a password input (replacing
window.confirm), mirroring the TOTP disable dialog. Backend error
messages (e.g. wrong password) are surfaced instead of the generic
failure toast. Rename remains password-free as it is cosmetic.
feeeei