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

KanbanTests/BannerCenterTests.swift

@@ -375,6 +375,24 @@ struct BannerCenterPhrasingTests {
             != BannerCenter.headline(for: error(.style(title: "Fix login"))))
     }
 
+    @Test("The trash trio speaks the board's vocabulary, never the system Trash's")
+    func trashVerbsFollowTheNamingConstraint() {
+        // 03-board-ui.md § Trash's naming constraint, settled with the trash UI copy: two "Trash"
+        // concepts coexist, and "Finder's 'Move to Trash' phrasing is reserved for the system Trash;
+        // board deletion says 'Delete'". A banner is UI copy like any other.
+        #expect(BannerCenter.headline(for: error(.delete(title: "Fix login"), .io(message: "the disk is full")))
+            == "Couldn't delete 'Fix login' — the disk is full")
+        #expect(BannerCenter.headline(for: error(.restore(title: "Fix login"), .io(message: "the disk is full")))
+            == "Couldn't put 'Fix login' back — the disk is full")
+        #expect(BannerCenter.headline(for: error(.purge(title: "Fix login"), .io(message: "the disk is full")))
+            == "Couldn't permanently delete 'Fix login' — the disk is full")
+
+        for operation in [WriteOperation.delete(title: "Fix login"), .delete(title: nil)] {
+            #expect(!BannerCenter.headline(for: error(operation)).contains("Trash"))
+            #expect(!BannerCenter.headline(for: error(operation)).contains("trash"))
+        }
+    }
+
     @Test("The cause tail comes from the error's reason and nowhere else")
     func causeTailCarriesTheDiagnosis() {
         #expect(BannerCenter.headline(for: error(.move(title: "Fix login"), .io(message: "the disk is full")))