Does your Constitution restrain Canberra from forcing your premier to cut ties with the Chicomms?
No.
Basically the Australian constitution gives the Commonwealth government specific areas of responsibility and everything else is under state control.
But the first of those specific areas listed is 'Trade and commerce with other countries, and among the States'. Another is 'External affairs'.
Either of these create a 'head of power' for the Commonwealth the constitutional power to overrule a state government on something like China's 'Belt and Road' initiative. Legislation needs to be passed for that to happen, and the Commonwealth government is planning such legislation, but absent some extraordinary and novel legal argument from Victoria (can never entirely rule that out), it will past constitutional muster.