Halcyon is a ready-to-run admin dashboard for a fictional online shop with KPI cards, hand-written SVG line / bar / donut / heatmap charts, an orders table with sort, search, filter, pagination, column toggle and CSV export, an activity feed, settings, and a date range selector that re-computes every widget. All data access lives in js/api.js with TODO markers for your backend. Written in vanilla JavaScript with a component-style structure so it ports easily to React / Next.js; it is not a React project and has no build step.