Add dashboard analytics

Shortcake-Parent: 2026-08-06-add-conference-switcher

Author: patrick91

backend/dashboard/package.json

@@ -16,6 +16,7 @@
     "radix-ui": "^1.6.7",
     "react": "19.2.8",
     "react-dom": "19.2.8",
+    "recharts": "3.8.0",
     "shadcn": "^4.16.1",
     "tailwind-merge": "^3.6.0",
     "tw-animate-css": "^1.4.0"