Let \( f:[0,\infty) \to \mathbb{R} \) be a differentiable function such that \( f(x)=1-2x+\int_{0}^{x} e^{x-t}f(t)\,dt \) for all \( x \in [0,\infty) \). Then the area of the region bounded by \( y=f(x) \) and the coordinate axes is:
\( \sqrt{5} \)
\( 2 \)
\( \frac{1}{2} \)
\( \sqrt{2} \)