deps: bump @tailwindcss/postcss from 4.1.16 to 4.1.18

Bumps [@tailwindcss/postcss](https://github.com/tailwindlabs/tailwindcss/tree/HEAD/packages/@tailwindcss-postcss) from 4.1.16 to 4.1.18.
- [Release notes](https://github.com/tailwindlabs/tailwindcss/releases)
- [Changelog](https://github.com/tailwindlabs/tailwindcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/tailwindlabs/tailwindcss/commits/v4.1.18/packages/@tailwindcss-postcss)

---
updated-dependencies:
- dependency-name: "@tailwindcss/postcss"
  dependency-version: 4.1.18
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -40,7 +40,7 @@
         "@babel/preset-react": "^7.28.5",
         "@babel/preset-typescript": "^7.28.5",
         "@eslint/js": "^9.39.1",
-        "@tailwindcss/postcss": "^4.1.16",
+        "@tailwindcss/postcss": "^4.1.18",
         "@testing-library/dom": "^10.4.1",
         "@testing-library/jest-dom": "^6.9.1",
         "@testing-library/react": "^16.2.0",