connect via link with simplex: protocol (#251)

apps/ios/Shared/Model/ChatModel.swift

@@ -17,6 +17,8 @@ final class ChatModel: ObservableObject {
     @Published var chatItems: [ChatItem] = []
     @Published var terminalItems: [TerminalItem] = []
     @Published var userAddress: String?
+    @Published var appOpenUrl: URL?
+    @Published var connectViaUrl = false
 }
 
 class User: Decodable {

apps/ios/Shared/Model/SimpleXAPI.swift

@@ -402,10 +402,15 @@ private func encodeCJSON<T: Encodable>(_ value: T) -> [CChar] {
 }
 
 enum ChatError: Decodable {
+    case error(errorType: ChatErrorType)
     case errorStore(storeError: StoreError)
     // TODO other error cases
 }
 
+enum ChatErrorType: Decodable {
+    case invalidConnReq
+}
+
 enum StoreError: Decodable {
     case userContactLinkNotFound
     // TODO other error cases