Card windows drop the title from the title bar — the body already says it

The card's name renders as part of the card body, so the chrome said it
twice. HostedWindowController gains a titleVisibility slot on the same
retained-slot pattern as the accessory and toolbar (reapplied at attach,
so the macOS 26 provisional-window swap can't lose it); CardWindowHost
opts in beside installToolbar, board windows keep AppKit's default.
window.title itself is untouched — navigationTitle still feeds the
Window menu, Exposé, VoiceOver and restoration.

Known consequence, probed empirically: under .hidden AppKit collapses
title and subtitle into one hidden field, so the "board › lane"
navigationSubtitle disappears with it — and the details sidebar carries
no placement rows, so a card window currently shows its home nowhere.
Filed on the Redesign board to bless or relocate; 05-card-window.md's
subtitle sentence needs reconciling either way.

Claude-Session: https://claude.ai/code/session_01CqjXB7ASoWtbyoGod68k97

Kanban/App/CardWindowHost.swift

@@ -851,6 +851,16 @@ struct CardWindowHost: View {
             CardToolbar.controller(body: bodyPresentation, rawSource: rawSource, attachments: attachments)
         )
 
+        // **No title in the title bar** — the card's name is shown as part of the card's body
+        // instead (the large-title text at the top of the body column, `bodyColumn`), so the chrome
+        // does not say it twice. `window.title` itself is untouched — `.navigationTitle(windowTitle)`
+        // on this view still sets it every time the card renames or a new card's window opens — so
+        // the Window menu, Mission Control/Exposé, VoiceOver and state restoration all keep naming
+        // this window correctly; only the title *bar's* rendering of that string is suppressed
+        // (`HostedWindowController.hideTitle`). Board windows call no such thing and keep AppKit's
+        // default (`.visible`), which is where their title lives.
+        windowController.hideTitle()
+
         // **This window's own stack** (13-native-undo.md ▸ Rules ▸ two levels, re-ruled 2026-07-31 —
         // superseding the shared-stack wiring): "a card window owns its own stack for the session it
         // represents ... and `window.undoManager` answers with it (standard per-window AppKit