Refactor all CSS to use Tailwind CSS v4 (#66)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: Boshen <[email protected]>

Author: Copilot

apps/dashboard/package.json

@@ -17,10 +17,12 @@
     "recharts": "^2.12.6"
   },
   "devDependencies": {
+    "@tailwindcss/vite": "^4.1.13",
     "@types/react": "^19.1.10",
     "@types/react-dom": "^19.1.7",
     "@types/react-router-dom": "^5.3.3",
     "rolldown-vite": "7.1.5",
+    "tailwindcss": "^4.1.13",
     "typescript": "catalog:"
   }
 }