Replaces flat Card-based KPI rendering with KPITile (gradient-brand-soft + accent stripe). Adds polished gradient PageHeader to DashboardShell with eyebrow, KPI sub-line, description. Tile-shaped skeletons replace the four CardSkeletons during KPI load. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>