review PDF report generation in Qt6

[atsju]

Qt6 managing scaling better or maybe has better picture printing and scaling integration than 5Y ago
Anyway, PDF report generation should be reviewed to be pretty for everybody on any computer and screen.

#269 (comment)

[atsju]

@githubdoe Could you share a "good" PDF report for reference here ?

We could use it as baseline for comparison and detect problems.
We will also see if it's resolution dependent or not
And see if QT6 has broken/moved some things

[atsju]

@githubdoe can you kindly share a reference PDF report here in issue #271 ?

Between your screen specificities and QT6 upgrade I would like to ensure we have a reference report validated by you.