Because:
* Cancelled and timed-out passkey sign-ins are benign, but showed a red error
banner with no way forward.
This commit:
* Replaces the red error banner with an amber warning banner for a cancelled
ceremony ("Couldn’t sign in with a passkey" + a "How to use passkeys" link)
and, as a separate message, for a timeout ("Passkey sign-in timed out. Try
again."); genuine errors keep the error banner.
* Routes the help link to the how-to article on email-first and the
troubleshooting article on other surfaces, and adds a
passkey.get_help_link_click Glean event (reason = surface).
* Moves the passwordless-OTP "Code expired?" prompt below the Confirm button.
Refs #FXA-14171