Check the CloudKit schema when packaging and show broken iCloud sync

mac/Sources/Byre/Settings.swift

@@ -49,6 +49,8 @@ struct SettingsView: View {
                         try await store.api.client.updateReviewModels(body: .json(.init(reviewModel: me.reviewModel, secondReviewModel: m))).ok.body.json
                     }
                 }
+                heading("iCloud sync")
+                SyncState()
                 heading("This Mac's permissions")
                 Text("The macOS privacy grants byre's app needs for agents to see and control this Mac. Checking asks macOS for any that are missing.")
                     .foregroundStyle(Palette.muted)
@@ -97,6 +99,26 @@ private struct ServerColorPicker: View {
     }
 }
 
+private struct SyncState: View {
+    var body: some View {
+        TimelineView(.periodic(from: .now, by: 30)) { _ in
+            if let sync = Servers.shared.sync {
+                if sync.ok {
+                    Text("This Mac shares its servers, window colours, drafts and task visits through iCloud. Last synced \(ago(sync.at)).")
+                        .fixedSize(horizontal: false, vertical: true)
+                } else {
+                    Text("iCloud sync is failing on this Mac, so changes made here aren't reaching your other Macs. Failed \(ago(sync.at)): \(sync.error ?? "")")
+                        .foregroundStyle(Palette.danger)
+                        .textSelection(.enabled)
+                        .fixedSize(horizontal: false, vertical: true)
+                }
+            } else {
+                Text("No iCloud sync has finished since byre started.").foregroundStyle(Palette.muted)
+            }
+        }
+    }
+}
+
 private struct DeviceNotifications: View {
     @ViewState private var status: UNAuthorizationStatus?
     @ViewState private var asking = false