Fix multi-window, turn off sandboxing

kordophone2/SplitView.swift

@@ -0,0 +1,38 @@
+//
+//  SplitView.swift
+//  kordophone2
+//
+//  Created by James Magahern on 8/29/25.
+//
+
+import SwiftUI
+
+struct SplitView: View
+{
+    @State var conversationListModel = ConversationListView.ViewModel()
+    @State var transcriptViewModel = TranscriptView.ViewModel()
+    @State var entryViewModel = MessageEntryView.ViewModel()
+    
+    private let xpcClient = XPCClient()
+    private var selectedConversation: Display.Conversation? {
+        guard let id = conversationListModel.selectedConversations.first else { return nil }
+        return conversationListModel.conversations.first { $0.id == id }
+    }
+
+    var body: some View {
+        NavigationSplitView {
+            ConversationListView(model: $conversationListModel)
+                .frame(minWidth: 330.0)
+                .xpcClient(xpcClient)
+        } detail: {
+            ConversationView(transcriptModel: $transcriptViewModel, entryModel: $entryViewModel)
+                .xpcClient(xpcClient)
+                .selectedConversation(selectedConversation)
+                .navigationTitle("Kordophone")
+                .navigationSubtitle(selectedConversation?.displayName ?? "")
+                .onChange(of: conversationListModel.selectedConversations) { oldValue, newValue in
+                    transcriptViewModel.displayedConversation = newValue.first
+                }
+        }
+    }
+}