Report descriptions run to a paragraph. ReportDescription wraps Mantine's
Spoiler to clamp them to two lines, and the toggle only renders when the
text actually overflows.
PageHeader kept its subtitle on a hard truncate class, which would have
pinned the spoiler to one line, so a ReactNode subtitle now renders as-is
and owns its own layout. A string subtitle still truncates as before.
Title and subtitle grew unbounded, relying only on flex-squeeze from action
buttons to ever truncate. Caps the container at 640px and gives the
subtitle the same truncate treatment the title already had, so a long
page title or description (report descriptions in particular) always
ellipses instead of stretching the header.
