Layout fixes

[daringer]

• information_box now with consistent height and font-sizes
• consistent left margin for settings + secrets list/tree-view
• overall properly set font-sizes across all views
• increase font size in nk3-button on welcome view
• redesign welcome page
• corrected font size for algorithm drop-down to choose algorithm

[mmerklinger]

On Fedora 40 with Gnome desktop the dark mode has no effect, except for the title of the window. Turning on dark mode before or after the start of the app doesn't have an effect either.

[mmerklinger]

On Windows 11 without a connected Nitrokey the icon on the top left is misaligned and the text below it might not be perfectly centered.

[mmerklinger]

On Windows 11 the the container in the update window is cut off if the window size is reduced to the minimum size. When extended it will stop to expand at some fixed width.

[mmerklinger]

On Linux and Window the containers inside the Passwords and Settings tab have aligned containers. Changing from one of them to the Overview makes the container border jump a little bit. In the overview tab it seems that the elements have another container around them, because I can see a slight grey box around it.

[mmerklinger]

Could you please also remove the qt_material from the mypy override list in the pyproject.toml? It was originally changed in another PR, but I think it would fit thematically in this one.

[mmerklinger]

Could you please also remove the qt_material from the mypy override list in the pyproject.toml? It was originally changed in another PR, but I think it would fit thematically in this one.

Fixed in #307.

[mmerklinger]

PR tested on Fedora 41 and macOS 15.1. Minor problems left regarding dark mode. Overall great improvements.