feat: Refactor GameResource to use var injection for GameRegistry and ObjectMapper

modules/core/src/main/scala/de/nowchess/chess/resource/GameResource.scala

@@ -20,10 +20,19 @@ import jakarta.ws.rs.*
 import jakarta.ws.rs.core.{MediaType, Response}
 
 import java.util.concurrent.atomic.AtomicReference
+import scala.compiletime.uninitialized
 
 @Path("/api/board/game")
 @ApplicationScoped
-class GameResource(@Inject val registry: GameRegistry, @Inject val objectMapper: ObjectMapper):
+class GameResource:
+
+  // scalafix:off DisableSyntax.var
+  @Inject
+  var registry: GameRegistry = uninitialized
+
+  @Inject
+  var objectMapper: ObjectMapper = uninitialized
+  // scalafix:on DisableSyntax.var
 
   private val DefaultWhite = PlayerInfo(PlayerId("p1"), "Player 1")
   private val DefaultBlack = PlayerInfo(PlayerId("p2"), "Player 2")