…overlap (#34918)

This shows the title in the top corner of the rect if there's enough
space.

The complex bit here is that it can be noisy if too many boundaries
occupy the same space to overlap or partially overlap.

This uses an R-tree to store all the rects to find overlapping
boundaries to cut the available space to draw inside the rect. We use
this to compute the rectangle within the rect which doesn't have any
overlapping boundaries.

The roots don't count as overlapping. Similarly, a parent rect is not
consider overlapping a child. However, if two sibling boundaries occupy
the same space, no title will be drawn.

<img width="734" height="813" alt="Screenshot 2025-10-19 at 5 34 49 PM"
src="https://github.com/user-attachments/assets/2b848b9c-3b78-48e5-9476-dd59a7baf6bf"
/>

We might also consider drawing the "Initial Paint" title at the root but
that's less interesting. It's interesting in the beginning before you
know about the special case at the root but after that it's just always
the same value so just adds noise.