Realign code with the 2026-07-29 accessibility rulings

Three ruled behavior changes (DESIGN/10, resolution session 2026-07-29):

- The board-change digest covers the trash while View > Show Trash is on:
  BoardDiff.between gains includingTrash, keying its card index by
  ItemPath so foreign purges, restores, and Empty Trash join the digest;
  crossings of the trash boundary still read deleted/restored, never
  moved, on both sides of the toggle. BoardStore.land passes the store's
  own isTrashVisible - no new injection seam.

- A vanished head with surviving co-selection is still named: naming and
  recovery are independent axes, so BoardAnnouncer's vanished-focus rung
  fires on all branches while the survivors-veto now gates only the
  recovery half (recovery implies vanished, no longer both-or-neither).

- Banner-row buttons are literal FKA Tab stops: BannerRow.controls is
  the row's testable button inventory, BannerRowView renders from it
  with .focusable() on each button; the combined VoiceOver element stays
  unconditional - custom actions and Tab stops are independent surfaces.

19 tests added, 2 expectations updated to the rulings. 1607 green on
both schemes.

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

Kanban/UI/BannerStripView.swift

@@ -154,7 +154,12 @@ private struct BannerRowView: View {
         .background(row.tone.fill)
         // One element per row, tone included: a VoiceOver user must hear *that* this is an error
         // before hearing what the error is, and colour cannot carry that. The dismiss and Cancel
-        // buttons survive as custom actions of the combined element rather than as separate stops.
+        // buttons stay inside the combined element, where VoiceOver surfaces them as the row's
+        // custom actions — **and are Tab stops in their own right besides** (see `trailingControls`:
+        // 10-accessibility.md ▸ Full Keyboard Access, ruled 2026-07-29). The two are independent
+        // surfaces, so the combine is unconditional: nothing here is uncombined under FKA, because
+        // the focus loop does not need the AX tree's permission to include a button and a VoiceOver
+        // user would otherwise hear a different row depending on a keyboard setting.
         //
         // The label is composed by `AccessibilityPhrases` rather than spelled here because the two
         // standing conditions are also *announced* on arrival and clearance (10-accessibility.md ▸
@@ -180,26 +185,49 @@ private struct BannerRowView: View {
         }
     }
 
+    /// The row's buttons, rendered straight from `BannerRow.controls` — **the Tab loop the FKA
+    /// ruling asks for** (10-accessibility.md ▸ Full Keyboard Access, 2026-07-29: "'Every control'
+    /// is literal and includes banner-row buttons … FKA serves sighted keyboard-only users, to whom
+    /// VO custom actions are invisible, and Cancel on an in-progress operation is exactly the
+    /// control that cannot require a pointer").
+    ///
+    /// Driven from the row's inventory rather than from a pair of `if`s over the same data, so what
+    /// a row's controls *are* is one testable fact (`BannerCenterTests`) instead of a view detail
+    /// that a headless suite cannot see.
     @ViewBuilder
     private var trailingControls: some View {
-        if case let .inProgress(operation) = row, let cancel = operation.cancel {
+        ForEach(row.controls) { control in
+            button(for: control)
+                // **A literal tab stop**, and the focus ring left on to show it — the style editor's
+                // wells' rule, for its reason: these are controls, not window furniture, so unlike
+                // the board strip (`BoardView`) there is nothing here to suppress. Stated on the
+                // button rather than left to the button style, because `.plain` and `.link` render
+                // as bare content and the combine above puts them inside another accessibility
+                // element: the focus item is asked for outright so neither can quietly cost the row
+                // its keyboard reach.
+                .focusable()
+        }
+    }
+
+    @ViewBuilder
+    private func button(for control: BannerRowControl) -> some View {
+        switch control {
+        case let .cancel(cancel):
             // Cancel appears on safe copies only (02, settled): it means "remove the partial copy,
             // nothing lost". Git brackets pass no closure and therefore get no button.
-            Button("Cancel", action: cancel)
+            Button(control.label, action: cancel)
                 .buttonStyle(.link)
                 .font(.callout)
-        }
-
-        if let dismissID = row.dismissID {
+        case let .dismiss(id):
             Button {
-                onDismiss(dismissID)
+                onDismiss(id)
             } label: {
                 Image(systemName: "xmark")
                     .imageScale(.small)
             }
             .buttonStyle(.plain)
-            .accessibilityLabel("Dismiss")
-            .help("Dismiss")
+            .accessibilityLabel(control.label)
+            .help(control.label)
         }
     }
 }