Draft: fix tapping on zbar code coordinates mismatch

Second commit to fix behaviour described in issue #50 , 1st was about red area position, this is about tapping area to trigger zbar code informative dialog. The alignment between the area of the zbar code and the area where tapping triggers on_zbar_code_tapped function is not yet perfect. Nevertheless, behaviour with this MR is way better than actual situation on my PinePhone with Mobian Bookworm. Alignment of the tapping area on the red zbar preview area is perfect in portrait position. In landscape position, the tapping area covers the red area and extends a bit on the left, too.

I have identified this merge request as "draft" because this is not yet perfect, nor has it been tested on other devices, then feel free to test/improve this.