Cache wallet balance and activity so screens show it instantly

apps/ios/Koins/Models.swift

@@ -18,12 +18,12 @@ struct WalletRecord: Codable, Identifiable, Equatable {
   var createdAt: Date
 }
 
-enum Direction {
+enum Direction: String, Codable {
   case incoming
   case outgoing
 }
 
-struct TransactionRecord: Identifiable {
+struct TransactionRecord: Identifiable, Codable {
   let id: String
   let amount: String
   let timestamp: Date?
@@ -44,12 +44,21 @@ struct TransactionRecord: Identifiable {
 
 }
 
-struct Balance {
+struct Balance: Codable {
   var total: String
   var unlocked: String
   var funded: Bool
 }
 
+/// Persisted per chain so a switch or relaunch shows the last-known state
+/// instantly while the network catches up.
+struct ChainCache: Codable {
+  var balance: Balance
+  var transactions: [TransactionRecord]
+  var accounts: [MoneroAccount]?
+  var savedAt: Date
+}
+
 struct SyncStatus {
   var height: UInt64
   var daemonHeight: UInt64
@@ -78,7 +87,7 @@ enum TransactionPriority: Int {
   }
 }
 
-struct MoneroSubaddress: Identifiable {
+struct MoneroSubaddress: Identifiable, Codable {
   let accountIndex: Int
   let index: Int
   let address: String
@@ -90,7 +99,7 @@ struct MoneroSubaddress: Identifiable {
   var id: String { "\(accountIndex)/\(index)" }
 }
 
-struct MoneroAccount: Identifiable {
+struct MoneroAccount: Identifiable, Codable {
   let index: Int
   let address: String
   let balance: String