v0.56.2

Fixed

• The Agent card no longer offers a primary "Sign in" while an ACP agent
  is already connected. The card now has four distinct shapes: signed
  out (primary "Sign in" plus the how-to hint), signing in (status,
  Cancel and the browser link), connecting ("Connecting to {agent}...",
  no buttons) and signed in (the sign-in method line and a plain "Switch
  account"). Design note
  docs/design-notes/2026-09-17-acp-account-card-phases.md.