Is it permissible to include a clause in the marriage contract stipulating partnership between the spouses in everything after marriage?

The aforementioned partnership contract is impermissible because it involves ambiguity (Jahalah) and uncertainty (Gharar), and the Prophet, peace and blessings be upon him, forbade transactions involving Gharar.

It is also impermissible to combine a partnership or sales contract with a marriage contract in a single agreement. Marriage is based on leniency and forgiveness (musamahah), while sales and partnerships are based on strict bargaining and contention (mushahah). If they are combined, the contract becomes void, and the marriage becomes فاسد (fasid - invalid or corrupt). Such a marriage must be dissolved before consummation, and if consummated, it is affirmed with a dower of the like (Sadaq al-Mithl).

And Allah knows best.