Sidebar: highlight the Working shelf header instead of Snoozed

[rajuptvs]

With the Working section on, the Snoozed header is the only shelf header drawn in blue. Working and Settled are both muted gray. So when all three shelves are collapsed, the one that stands out is the shelf where nothing is happening:

The Working shelf has a thread running right now, but it's the Snoozed header that's highlighted.

The tint doesn't depend on what the shelf holds. SidebarSectionHeader in apps/web/src/components/Sidebar.tsx hard-codes the tone:

tone={props.isDropTarget ? "accent" : props.dragging ? "emphasized" : snoozed ? "info" : "muted"}

Snoozed threads are the ones I've set aside on purpose, so I'd expect that header to be the quietest. Working holds the threads that might need me soon, and the Working status label on its rows is already text-info. Right now the header and its rows don't match.

Possible changes:

1. Swap the tones. Working gets info and Snoozed goes to muted.
2. Tint by content. Working gets info only when it has at least one thread, and every other header stays muted. An empty Working shelf then stays gray, and a collapsed shelf with live work stands out.

I'd lean toward 2, since an empty Working shelf has nothing to call attention to. Was the blue Snoozed header a deliberate choice, and would a small PR for one of these be welcome?