I believe that I've successfully deployed my (very basic) site to fortrabbit, but as soon as I connect to SSH to run some commands (such as
php artisan migrate
php artisan db:seed
SQLSTATE[HY000]  No such file or directory
The error message indicates that a MySQL connection via socket is tried (which is not supported).
In the context of Laravel (artisan), you probably want to use a different / the correct environment. Eg:
php artisan migrate --env=production (or whatever environment). See here.