Is the ʿiddah after khulʿ or judicial dissolution (fasakh) the same as after talaq?

Yes, in the Shafi'i school the ʿiddah after khulʿ and fasakh is the same as the ʿiddah of talaq: three quru' (three periods of purity), three months, or until delivery.
The difference is that both are irrevocable (ba'in) separations, so the husband cannot take her back during the ʿiddah. If they wish to reunite, a new contract and mahr are needed, and this can be done even during the wife's own ʿiddah.
A pregnant wife is entitled to maintenance until she gives birth. In the Shafi'i school, fasakh does not reduce the number of talaq, but khulʿ counts as one talaq. See ʿiddah & rujuk.