Recolour: the only colour is exposure

The palette collapses to warm grayscale with a single accent. Ember
appears only where the target is observed — a public deposit, a
linkable amount, an adversary finding. Everything private is calm and
colourless, so the design language and the product thesis become the
same statement.

Indigo, blue and the second "good" accent are gone entirely; cool
whites and blacks are warmed to paper and ink. StateBadge now makes
sealed and seen unmistakable: private is solid ink, public is the one
chip that carries colour.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>