Try running tailwind through npx prefix

See if this fixes a permission error on Render.

```
/usr/bin/bash: line 1: /opt/render/project/src/node_modules/.bin/tailwindcss: Permission denied
error: script "build:css" exited with code 126
```

Author: javierjulio

package.json

@@ -6,7 +6,7 @@
     "tailwindcss": "^3.4.18"
   },
   "scripts": {
-    "build:css": "tailwindcss -i ./app/assets/stylesheets/active_admin.css -o ./app/assets/builds/active_admin.css --minify -c tailwind-active_admin.config.js"
+    "build:css": "npx tailwindcss -i ./app/assets/stylesheets/active_admin.css -o ./app/assets/builds/active_admin.css --minify -c tailwind-active_admin.config.js"
   },
   "packageManager": "yarn@1.22.19"
 }