Add a Vite + React 19 + Tailwind v4 + Recharts SPA (dash/) and a 'web'
command that serves the built UI plus a local /api/usage endpoint backed
by the existing menubar aggregation. Midnight theme with CodeBurn's
orange chart ramp: hero cost, a stacked-by-model daily bar chart with a
custom tooltip and hover-dim, metric cards, by-tool and by-activity bar
lists, and top-projects and tools tables. Period and provider filters,
react-query with skeleton loading. Stays 100% local.
build:dash builds the SPA into dist/dash (shipped via package files,
served at runtime); a missing build falls back to a helpful message.
