iOS: gate capabilities by permissions and add settings controls

apps/ios/Sources/Model/NodeAppModel+Permissions.swift

@@ -0,0 +1,22 @@
+import Foundation
+import UIKit
+
+@MainActor
+extension NodeAppModel {
+    func permissionSnapshot() -> IOSPermissionSnapshot {
+        IOSPermissionCenter.statusSnapshot()
+    }
+
+    @discardableResult
+    func requestPermission(_ permission: IOSPermissionKind) async -> IOSPermissionSnapshot {
+        _ = await IOSPermissionCenter.request(permission)
+        return IOSPermissionCenter.statusSnapshot()
+    }
+
+    func openSystemSettings() {
+        guard let url = URL(string: UIApplication.openSettingsURLString) else {
+            return
+        }
+        UIApplication.shared.open(url)
+    }
+}