The hover-reveal overlay showed only the nav rail — session rows, search,
pinned/recents were gated behind `sidebarOpen` (false while collapsed), so
they never mounted in the floated panel.
Add a $sidebarRevealed store the PaneShell overlay drives via a new
onHoverRevealChange callback, and gate ChatSidebar's content on
`sidebarOpen || sidebarRevealed` (contentVisible) instead of raw open
state. The overlay now shows the complete sidebar.
Brooklyn Nicholson
3e455726eb