feat: Passkey (WebAuthn) login (#1111)

* feat(auth): passkey (WebAuthn) login — server endpoints, schema + admin toggle

Add @simplewebauthn/server registration and primary (discoverable) login ceremonies under /api/auth/passkey, a webauthn_credentials + single-use webauthn_challenges schema (migration), the instance-wide passkey_login toggle (default off) enforced before auth by a guard, and require_mfa satisfaction via a verified passkey. RP ID/origin come only from server config (webauthn_rp_id/origins -> APP_URL), never request headers.

* feat(auth): passkey enrolment, login button + admin settings UI

PasskeysSection in account settings (add/rename/remove with a current-password step-up), a 'Sign in with a passkey' button on the login page, the admin enable + RP-ID/origins controls, and a per-user admin reset action.

* i18n(auth): passkey strings across all locales

Add login/settings/admin passkey keys to en and all 19 translated locales.

shared/src/i18n/ko/login.ts

@@ -89,5 +89,7 @@ const login: TranslationStrings = {
   'login.resetPasswordInvalidLinkBody':
     '이 링크가 없거나 손상되었습니다. 새 링크를 요청하세요.',
   'login.resetPasswordFailed': '재설정 실패. 링크가 만료되었을 수 있습니다.',
+  'login.passkey.signIn': '패스키로 로그인',
+  'login.passkey.failed': '패스키 로그인에 실패했습니다. 다시 시도하세요.',
 };
 export default login;