feat: Improved how NNUE Evalutes

modules/ui/src/main/scala/de/nowchess/ui/Main.scala

@@ -1,6 +1,6 @@
 package de.nowchess.ui
 
-import de.nowchess.api.board.Color.Black
+import de.nowchess.api.board.Color.{Black, White}
 import de.nowchess.bot.util.PolyglotBook
 import de.nowchess.bot.BotDifficulty
 import de.nowchess.bot.bots.{ClassicalBot, HybridBot, NNUEBot}
@@ -16,10 +16,9 @@ object Main:
     // Create the core game engine (single source of truth)
     val engine = new GameEngine()
 
-
     val book = PolyglotBook("../../modules/bot/codekiddy.bin")
 
-    engine.setOpponentBot(HybridBot(BotDifficulty.Easy, book = Some(book)), Black);
+    engine.setOpponentBot(HybridBot(BotDifficulty.Easy, book = Some(book)), White);
 
     // Launch ScalaFX GUI in separate thread
     ChessGUILauncher.launch(engine)

modules/ui/src/main/scala/de/nowchess/ui/gui/PieceSprites.scala

@@ -6,24 +6,26 @@ import de.nowchess.api.board.{Color, Piece, PieceType}
 /** Utility object for loading chess piece sprites. */
 object PieceSprites:
 
-  private val spriteCache = scala.collection.mutable.Map[String, Option[Image]]()
+  private val spriteCache = scala.collection.mutable.Map[String, Image]()
 
   /** Load a piece sprite image from resources. Sprites are cached for performance.
     */
-  def loadPieceImage(piece: Piece, size: Double = 60.0): Option[ImageView] =
-    val key = s"${piece.color.label.toLowerCase}_${piece.pieceType.label.toLowerCase}"
-    spriteCache.getOrElseUpdate(key, loadImage(key)).map { image =>
-      new ImageView(image) {
-        fitWidth = size
-        fitHeight = size
-        preserveRatio = true
-        smooth = true
-      }
+  def loadPieceImage(piece: Piece, size: Double = 60.0): ImageView =
+    val key   = s"${piece.color.label.toLowerCase}_${piece.pieceType.label.toLowerCase}"
+    val image = spriteCache.getOrElseUpdate(key, loadImage(key))
+
+    new ImageView(image) {
+      fitWidth = size
+      fitHeight = size
+      preserveRatio = true
+      smooth = true
     }
 
-  private def loadImage(key: String): Option[Image] =
+  private def loadImage(key: String): Image =
     val path = s"/sprites/pieces/$key.png"
-    Option(getClass.getResourceAsStream(path)).map(new Image(_))
+    Option(getClass.getResourceAsStream(path)) match
+      case Some(stream) => new Image(stream)
+      case None         => sys.error(s"Could not load sprite: $path")
 
   /** Get square colors for the board using theme. */
   object SquareColors: