Implement toolbar customization for both windows

NSToolbar through the existing HostedWindowController rather than
SwiftUI's toolbar — for reasons that are contract, not taste: 03's
transient-search clause is a decision over the toolbar's current
contents, which NSToolbar publishes and SwiftUI's API cannot answer;
Undo/Redo are the system's nil-target responder-chain actions so the
toolbar items validate exactly as the menu rows do (disabled on base
boards, alive in m8 unchanged); and the search item hosts the real
NSSearchField with explicit first-responder control. Customization is
all system furniture — Customize sheet, drag rearrange, display-mode
popup, overflow, autosaved per window kind. Board default: the search
field alone, trailing; catalog adds New Card, New Lane, Undo, Redo,
Show Trash, every action extracted from its menu command so no second
predicate exists. Card default: the Edit Body / Raw Source toggles and
Add Attachment, mirroring their commands' own predicates live via
observation tracking. Removing the search item keeps the promise —
⌘F surfaces the same field as a transient strip under the title bar,
persisting until the query clears, and an overflowed item that cannot
take the keyboard falls through to the strip too.

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

Kanban/App/CardWindowHost.swift

@@ -515,6 +515,14 @@ struct CardWindowHost: View {
         // caller just registered against it), and the record id is what both memories are keyed on.
         let recordID = appModel.session(for: ref.board)?.recordID
 
+        // The window's customizable toolbar — Edit Body · Raw Source · Add Attachment, "the
+        // window's three committed functions" (03-board-ui.md ▸ Toolbar; 05-card-window.md ▸
+        // Window). It carries the three window-scoped handles above rather than a store, which is
+        // why it is installed here and not at attach: those are this window's, and so is it.
+        windowController.installToolbar(
+            CardToolbar.controller(body: bodyPresentation, rawSource: rawSource, attachments: attachments)
+        )
+
         windowController.onAttach = { window in
             if let recordID,
                let saved = appModel.boardRegistry.cardWindowFrame(id: recordID, cardID: ref.cardIdentity) {