What is the lowest temperture I can use to cook fresh pasta?
Cooking pasta at a full rolling boil (100°C at sea level or less at higher altitudes) is just conventional, it is not the boiling the cooks pasta but the temperature:

pasta cooking is influenced by three factors: water penetration inside the pasta, gelatinization of the starch (it normally occurs at a temperature between 60°C and 70°C for wheat starch) and the denaturation and consequent coagulation of gluten (at 70°C-80°C).
A temperature above 80°C for a certain time (slightly longer than what you'd need at 100°C to compensate for the slower penetration of water into the pasta) should guarantee a perfectly cooked pasta. 

This is the same for dried pasta and for fresh pasta; fresh will cook in less time, and you should probably taste it during the cooking process to find the right texture. 

The rolling boil helps to keep the pasta well separated and to avoid sticking, but a water circulator would probably take care of that too