Let \( f \) be a twice differentiable function such that \( f(x)=\int_{0}^{x}\tan(t-x)\,dt-\int_{0}^{x}f(t)\tan t\,dt \), \( x \in \left(-\dfrac{\pi}{2},\dfrac{\pi}{2}\right) \). Then \( f'\!\left(\dfrac{\pi}{6}\right)+12f'\!\left(-\dfrac{\pi}{6}\right)+f\!\left(\dfrac{\pi}{6}\right) \) is equal to ________.
