Patch. The collapse control on a [sidebar](https://docs.wirekit.app/components/sidebar) moves
to the bottom of the column, where this library's own documentation already said it was.

### Fixed

- **The collapse control sits below the navigation.** It was the first child of the column, so
  it rendered at the top — while the page describing it told the reader to click the chevron
  at the bottom, and while the [app rail](https://docs.wirekit.app/components/app-rail)'s
  expander really is down there. One gesture, two components, two places to look for it.
- **It no longer shares an edge with the row beside it.** The column carried no row gap, so
  the control's hover surface ended at exactly the pixel where the adjacent
  [`sidebar.item`](https://docs.wirekit.app/components/sidebar)'s began. Two surfaces of the same gray touching read as one smudged block rather than as two
  controls — and on a collapsed rail, where both are icon-sized squares, nothing else tells
  them apart. The column now spaces its rows by the token they were already spaced by.