For completeness, here is the location of the sensor in one of the battery teardown photos
(thanks, Dani!). It's normally hidden under a plastic cover that holds the five star-point ("dummy") connectors, and the world's largest CAN bus termination resistor.
This area is located towards the front left of the car. [ Edit: the current sensor is measuring the negative end of the battery, before the main negative contactor. ]
Here is the plastic cover with the termination resistor and current sensor (just dangling as it's removed from the pack):
The "12" on the end may indicate 120Ω: