chore(dependencies): update Tailwind CSS and related packages for improved styling

- Added @tailwindcss/postcss as a new dependency.
- Updated tailwindcss to version 4.1.11 for enhanced features and performance.
- Upgraded prettier-plugin-tailwindcss to version 0.6.13 for better formatting support.
- Adjusted postcss.config.js to use the new Tailwind CSS plugin structure.
- Removed the obsolete tailwind.config.js file as it is no longer needed.

worklenz-frontend/package.json

@@ -60,6 +60,7 @@
     "worklenz": "file:"
   },
   "devDependencies": {
+    "@tailwindcss/postcss": "^4.1.11",
     "@testing-library/jest-dom": "^6.6.3",
     "@testing-library/react": "^16.3.0",
     "@testing-library/user-event": "^14.6.1",
@@ -73,11 +74,10 @@
     "@types/react-dom": "19.0.0",
     "@types/react-window": "^1.8.8",
     "@vitejs/plugin-react": "^4.3.4",
-    "autoprefixer": "^10.4.20",
     "postcss": "^8.5.2",
-    "prettier-plugin-tailwindcss": "^0.6.8",
+    "prettier-plugin-tailwindcss": "^0.6.13",
     "rollup": "^4.40.2",
-    "tailwindcss": "^3.4.17",
+    "tailwindcss": "^4.1.11",
     "terser": "^5.39.0",
     "typescript": "^5.7.3",
     "vite": "^6.3.5",