Impose the Three-Mode Theme System on augment-it

augment-it adopts the Lossless theme religion — the two-tier token system and the light/dark/vibrant three-mode contract from the Astro Knots blueprint — adapted for a non-Astro, non-Tailwind, federated multi-remote app. A shared packages/theme holds one theme.css (named tokens → semantic tokens, three mode blocks) and one SSR-safe mode-switcher; the shell renders a 3-mode toggle in its chrome; every hardcoded hex across the shell and the two remotes is replaced with a semantic var(). The structure is imposed in this work; the user then iterates the actual colours at the named-token tier without touching component code — which is the entire point of the two-tier system.