Let \( z_1 \) and \( z_2 \) be two complex numbers such that \( \arg(z_1-z_2)=\dfrac{\pi}{4} \) and \( z_1,\,z_2 \) satisfy the equation \( |z-3|=\operatorname{Re}(z) \). Then the imaginary part of \( z_1+z_2 \) is equal to ______.