Is there anything in any scripture that you know of that would say or imply moksha can be described as permanent samadhi on brahman or on parabrahman - as continuous abiding in/as Brahman? Or any other type of permanent samadhi?
Moksha is not continuous Samadhi. A person who has realized Brahman in Samadhi stays in that state of identification with Brahman regardless of what he does. It does not matter whether he is in samadhi or not.
To the sage who has realized Brahman, the mind, which is the cause of unreal fancies, becomes perfectly tranquil. This verily is his state of quietude, in which, identified with Brahman, he has constant enjoyment of the Bliss Absolute, the One without a second.
To the man who has realized his own nature, and drinks the undiluted bliss of the Self, there is nothing more exhilarating than the quietude that comes of a state of desireless.
The illumined sage, whose only pleasure is in the Self, ever lives at ease, whether going or staying, sitting or lying, or in any other condition.
The noble soul who has perfectly realized the Truth, and whose mind-functions meet with no obstruction, no more depends upon conditions of place, time, posture, direction, moral disciplines, objects of meditation and so forth. What regulative conditions can there be in knowing one's own Self?