Search and filters at the bottom; Spotlight shows filters, the editor changes them

1. Rest: the search bar and filters button sit at the bottom, above the tabs, and hide while you scroll. A count on the filters button is the only sign that filters are on.
2. Filters button: opens the full-screen filters editor (room for the more complex filters coming).
3. Search bar: opens Spotlight. Its field stays at the bottom with the same filters button beside it. Under the field, the applied filters show as grouped, read-only badges.
4. Filters button inside Spotlight: brings the same editor up in front. Closing it returns to your search, with results updated.