Let the domain of the function \( f(x) = \log_{2} \log_{4} \log_{6}(3 + 4x - x^{2}) \) be \( (a, b) \). If \[ \int_{0}^{b-a} [x^{2}] \, dx = p - \sqrt{q} - \sqrt{r}, \quad p, q, r \in \mathbb{N}, \, \gcd(p, q, r) = 1, \] where \([ \, ]\) is the greatest integer function, then \( p + q + r \) is equal to