Well it turns out that:
Front right brake caliper was stuck because the pad dislodged from the caliper and in between the brake dust shield and the rotor!

Two shims were also destroyed!

So we got them all out, cleaned it and reinstalled with new pads (they were already metal-to-metal!). Surprisingly they were only replaced last June or May, not even one year! Bled the brakes while we were at it and put in new DOT 3 fluid, took it for a drive and it's now OK.
So check your brakes once in a while! These cars don't have the warning indicators if the pads are running thin...