press v1.20.0

Brand identity: the press pilcrow mark and lockup across the CLI (a banner,
status glyphs, and the house palette), the docs site (favicon, nav lockup,
social card), and the README.

Added

• Brand identity: the pilcrow mark and the press. lockup. The docs site gains
  a favicon, a theme-swapped nav mark (ink badge on light, vermilion on dark),
  and a large social card (og:image/twitter:image); the README shows the
  theme-aware lockup. Assets live in site/brand/.
• CLI branding (press.brand): a running press with no command shows the
  block banner and tagline, and press all ends with a "your book is ready"
  line, in the house vermilion. Color is emitted only to a real terminal
  (honoring NO_COLOR/FORCE_COLOR), so piped output stays plain and
  scriptable.