Is trailing one's garment (isbal) in clothing forbidden, and is one punished for it? And what is the ruling on dress code at work?

All praise is due to Allah, and may peace and blessings be upon the Messenger of Allah, his family, and his companions. To proceed:

Islam has not specified a particular type of clothing, but it has set guidelines for Muslim attire, which are: that it must cover the 'awrah (private parts), not be form-fitting, not be excessively long (below the ankles for men), not be a garment of ostentation, not resemble the clothing of disbelievers or wrongdoers, and not involve extravagance. If these conditions are met, then one may wear what is appropriate for their custom and work.

And Allah knows best.