perf: Don't re-substring multiplayer file name every time you do anything, dammit

core/src/com/unciv/logic/multiplayer/OnlineMultiplayer.kt

@@ -302,7 +302,7 @@ class OnlineMultiplayer {
     fun changeGameName(game: OnlineMultiplayerGame, newName: String, onException: (Exception?)->Unit) {
         debug("Changing name of game %s to", game.name, newName)
         val oldPreview = game.preview ?: throw game.error!!
-        val oldLastUpdate = game.lastUpdate
+        val oldLastUpdate = game.getLastUpdate()
         val oldName = game.name
 
         val newFileHandle = files.saveGame(oldPreview, newName, onException)

core/src/com/unciv/logic/multiplayer/OnlineMultiplayerGame.kt

@@ -30,17 +30,16 @@ class OnlineMultiplayerGame(
     lastOnlineUpdate: Instant? = null
 ) {
     private val lastOnlineUpdate: AtomicReference<Instant?> = AtomicReference(lastOnlineUpdate)
-    val lastUpdate: Instant
-        get() {
-            val lastFileUpdateTime = Instant.ofEpochMilli(fileHandle.lastModified())
-            val lastOnlineUpdateTime = lastOnlineUpdate.get()
-            return if (lastOnlineUpdateTime == null || lastFileUpdateTime.isLargerThan(lastOnlineUpdateTime)) {
-                lastFileUpdateTime
-            } else {
-                lastOnlineUpdateTime
-            }
+    fun getLastUpdate(): Instant {
+        val lastFileUpdateTime = Instant.ofEpochMilli(fileHandle.lastModified())
+        val lastOnlineUpdateTime = lastOnlineUpdate.get()
+        return if (lastOnlineUpdateTime == null || lastFileUpdateTime.isLargerThan(lastOnlineUpdateTime)) {
+            lastFileUpdateTime
+        } else {
+            lastOnlineUpdateTime
         }
-    val name get() = fileHandle.name()
+    }
+    val name = fileHandle.name()
     var error: Exception? = null
 
     init {

core/src/com/unciv/ui/screens/multiplayerscreens/MultiplayerHelpers.kt

@@ -42,7 +42,7 @@ object MultiplayerHelpers {
             val (message) = LoadGameScreen.getLoadExceptionMessage(ex, "Error while refreshing:")
             descriptionText.appendLine(message)
         }
-        val lastUpdate = multiplayerGame.lastUpdate
+        val lastUpdate = multiplayerGame.getLastUpdate()
         descriptionText.appendLine("Last refresh: [${Duration.between(lastUpdate, Instant.now()).formatShort()}] ago".tr())
         val preview = multiplayerGame.preview
         if (preview?.currentPlayer != null) {