Merge branch 'antigravity'
This is Google Antigravity fixing up my visualization tool (which was
also generated with help from google, but of the normal kind).
It mostly went smoothly, although I had to figure out what the problem
with using the builtin rectangle select was. After telling antigravity
to just do a custom RectangleSelector, things went much better.
Is this much better than I could do by hand? Sure is.
* antigravity:
Refine visualization: Zoom, Shortcuts, and Layout
Implement RectangleSelector for custom zoom and fix whitespace
visualize: fix navigation fighting with manual zoom
visualize: implement independent keyboard navigation
visualize: add keyboard navigation (arrows/space)
visualize: show individual sample markers at high zoom levels
visualize: refine zoom behavior
visualize: improvement to memory usage and navigation