chore(deps-dev): bump @tailwindcss/postcss from 4.0.14 to 4.1.6

Bumps [@tailwindcss/postcss](https://github.com/tailwindlabs/tailwindcss/tree/HEAD/packages/@tailwindcss-postcss) from 4.0.14 to 4.1.6.
- [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/v4.1.6/packages/@tailwindcss-postcss)

---
updated-dependencies:
- dependency-name: "@tailwindcss/postcss"
  dependency-version: 4.1.6
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

package.json

@@ -58,7 +58,7 @@
   "devDependencies": {
     "@biomejs/biome": "1.9.4",
     "@mdx-js/loader": "^3.1.0",
-    "@tailwindcss/postcss": "^4.0.14",
+    "@tailwindcss/postcss": "^4.1.6",
     "@tailwindcss/typography": "^0.5.16",
     "@types/js-cookie": "^3.0.6",
     "@types/mdx": "^2.0.13",