If \( z \) is a complex number such that \( \dfrac{z-i}{z-1} \) is purely imaginary, then the minimum value of \( \left| z-(3+3i) \right| \) is:
\( 2\sqrt{2} \)
\( 2\sqrt{2}-1 \)
\( 3\sqrt{2} \)
\( 6\sqrt{2} \)