Let the parabola \( y = x^2 + px + q \) passing through the point \( (1, -1) \) be such that the distance between its vertex and the \( x \)-axis is minimum. Then the value of \( p^2 + q^2 \) is:
\( 2 \)
\( 4 \)
\( 5 \)
\( 8 \)