feat: replace Recharts dashboard chart with visx area chart

Integrated 21st.dev AreaChart component with animated crosshair,
spring-based tooltip, and date ticker. Uses brand orange for the
line/fill with dark-only CSS variables.

package.json

@@ -23,11 +23,18 @@
     "@stripe/stripe-js": "^8.7.0",
     "@tanstack/react-virtual": "^3.13.21",
     "@types/d3": "^7.4.3",
+    "@visx/curve": "^3.12.0",
+    "@visx/event": "^3.12.0",
+    "@visx/grid": "^3.12.0",
+    "@visx/responsive": "^3.12.0",
+    "@visx/scale": "^3.12.0",
+    "@visx/shape": "^3.12.0",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "cobe": "^0.6.5",
     "country-flag-icons": "^1.6.4",
     "d3": "^7.9.0",
+    "d3-array": "^3.2.4",
     "d3-scale": "^4.0.2",
     "framer-motion": "^12.23.26",
     "html-to-image": "^1.11.13",
@@ -41,6 +48,7 @@
     "react": "^19.2.3",
     "react-dom": "^19.2.3",
     "react-markdown": "^10.1.0",
+    "react-use-measure": "^2.1.7",
     "recharts": "^2.15.0",
     "sonner": "^2.0.7",
     "svg-dotted-map": "^2.0.1",
@@ -58,6 +66,7 @@
     "@tailwindcss/typography": "^0.5.19",
     "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.2",
+    "@types/d3-array": "^3.2.2",
     "@types/d3-scale": "^4.0.9",
     "@types/node": "^20.14.12",
     "@types/react": "^19.2.14",