Let \( f(t)=\int \frac{(1-\sin (\log_{e} t))}{(1-\cos (\log_{e} t))}\,dt,\; t>1 \). If \( f\!\left(e^{\pi/2}\right)=-e^{-\pi/2} \) and \( f\!\left(e^{\pi/4}\right)=\alpha e^{\pi/4} \), then \( \alpha \) equals:
\( 1+\sqrt{2} \)
\( -1-\sqrt{2} \)
\( -1-2\sqrt{2} \)
\( -1+\sqrt{2} \)