Remove the face carousel — one card presentation

03's resettlement reverses the pathfinder carry-over: the
selection-keyed dual presentation proved undesirable, so a card has one
presentation — selection changes styling, never geometry, and the
masonry never reflows on click. Deleted the carousel view (page dots,
glass underlay, scroll-tick monitor), the QuickLook thumbnail cache
(sole consumer), the pure paging/suppression rules, and the
sole-selected animation key — Motion now keys transactions on the
search query and the drop proposal only. The attachment chip stays as
the face's whole attachment story; viewing media is the card window's
job. No carousel state had leaked beyond the view layer.

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

Kanban/UI/Board/BoardView.swift

@@ -94,14 +94,6 @@ struct BoardView: View {
     /// the cards and trash rows only *register* into it (`MarqueeTargetRegistry`).
     @State private var marqueeTargets = MarqueeTargetRegistry()
 
-    /// This window's attachment thumbnails, for the sole-selected card's carousel (03-board-ui.md
-    /// § Card face). `@State` for the sessions' reason — one per window, living exactly as long as
-    /// the window, so a board that closes forgets the files it was showing (see
-    /// `AttachmentThumbnailCache` on why the window and not the app). Handed down through the
-    /// environment rather than threaded, since nothing between here and a card face has any use for
-    /// it.
-    @State private var thumbnails = AttachmentThumbnailCache()
-
     /// The name of the strip's coordinate space, which is what a drop out of the trash is resolved
     /// in: `LaneLayoutMath.laneIndex` reads an x measured from the strip's leading edge, outer margin
     /// included, and no global or lane-local space is that.
@@ -157,7 +149,6 @@ struct BoardView: View {
             .onDrop(of: boardDropTypes, delegate: StripDropDelegate(context: dropContext))
         }
         .background(boardBackground)
-        .environment(thumbnails)
         // The window-level fallback, *behind* the specific targets: a release over any in-window
         // region they don't cover commits the current proposal instead of leaking the session into a
         // cancel-snapback — the drop lands where the shadows show, which is what the shadows promise.