Passkey sign-in added; relative links resolve

Added

• Passkey sign-in — use Face ID, Touch ID, or a hardware security key to authenticate. Manage, rename, and remove passkeys from the account settings page.

Fixed

• Relative links in ingested release notes (e.g. /docs, ./changelog) now resolve against the vendor's domain when rendered — no more broken in-page navigation.
• Coverage-side release URLs now redirect to the canonical release page instead of returning 404.