Adds the design tokens the polish PRs (10a-e) will draw from:
shadow-xs/sm/md/lg/glow, radius scale tuned to spec, gradient utilities,
spring/smooth eases, and fast/base/slow durations. Introduces
StatusPill, KPITile, and EmptyState primitives plus a polished
PageHeader variant ('gradient') with optional eyebrow + KPI sub-line —
existing PageHeader callers stay on the plain variant.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>