Build the trash quasi-lane

Deletion becomes a two-stage, Finder-style story. File > Delete and
plain Backspace tombstone the live selection; View > Show Trash (no
chord — Shift-Cmd-T stays with the system's tab bar) reveals the
quasi-lane: trailing, one fixed width unit consumed only while shown,
hatched dimmed header, count badge, no new-card button, exempt from
resize and reorder alike. Its contents are a pure view over the
snapshot — the deterministic sort (deleted newest first, folder-name
ties, unparseable stamps oldest) interleaves card rows with a
tombstoned lane's single entry, whose count names what Put Back
returns; the ancestor walk is absolute, so an own-flag card beneath a
tombstoned lane has no row and recovery is deliberately two steps.
Put Back twins Delete on Cmd-Backspace with validation enabling
exactly one; restore fidelity is byte-perfect because nothing ever
moved. Delete Immediately confirms exactly where loss is real (every
board is mode-none today; the predicate names the git carve-out for
m7), Empty Trash always confirms with the true whole-board count,
and dragging a tombstoned card onto a live lane restores it there —
positional drops and cross-board locality arrive with m5's machinery.
The banner's delete phrasing drops "move to the trash" per the naming
constraint: board deletion says Delete, "Move to Trash" stays
reserved for the system Trash. 47 new tests.

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

Kanban/App/BoardWindowHost.swift

@@ -39,6 +39,11 @@ struct BoardWindowHost: View {
     /// menu item through the focus system, like the store.
     @State private var boardInfo = BoardInfoPresentation()
 
+    /// This window's purge alert, open or not (03-board-ui.md § Trash). `@State` for `boardInfo`'s
+    /// reason and reaching the menu bar the same way: Delete Immediately and Empty Trash… are
+    /// menu-bar items, and a menu item cannot present anything of its own.
+    @State private var trashConfirmations = TrashConfirmations()
+
     @State private var phase: Phase = .opening
 
     private enum Phase {
@@ -80,15 +85,18 @@ struct BoardWindowHost: View {
                 BoardView(
                     store: store,
                     window: { windowController.window },
+                    confirmations: trashConfirmations,
                     openCard: { cardID in
                         openWindow(id: WindowID.card, value: CardWindowRef(board: ref, cardID: cardID))
                     }
                 )
             }
             // "The board in front", for the menu items that act on it (`LaneWidthCommands`), and
-            // beside it the window's own popover flag, which is what File ▸ Board Info toggles.
+            // beside it the window's own popover flag, which is what File ▸ Board Info toggles, and
+            // its purge-alert host, which the trash's two confirmed commands raise.
             .focusedSceneValue(\.boardStore, store)
             .focusedSceneValue(\.boardInfo, boardInfo)
+            .focusedSceneValue(\.trashConfirmations, trashConfirmations)
         }
     }