Add CascadeMenu/CascadeRow: a menu whose rows reveal a side submenu on
hover with an open delay, a forgiving close delay, and a cursor→submenu
safe triangle — while the cursor sweeps toward an open submenu, hovers
over sibling rows are ignored, so a natural diagonal move never snaps the
target shut. The triangle geometry (pointInTriangle) is unit-tested.
Apply it to the org switcher: each organization reveals its actions
(switch / delete) on hover instead of a hidden hover-only "x", while the
destructive delete keeps its deliberate, non-hover-dismissible confirm.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>