Break out spawnable entities and use a registry to spawn them.

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

lib/features/entities/entity_registry.dart

@@ -0,0 +1,35 @@
+import 'package:wolf_dart/features/entities/decorative.dart';
+import 'package:wolf_dart/features/entities/enemies/brown_guard.dart';
+import 'package:wolf_dart/features/entities/entity.dart';
+
+typedef EntitySpawner =
+    Entity? Function(int objId, double x, double y, int difficultyLevel);
+
+abstract class EntityRegistry {
+  // Add future enemies (SSGuard, Dog, etc.) to this list!
+  static final List<EntitySpawner> _spawners = [
+    Decorative.trySpawn,
+    BrownGuard.trySpawn,
+  ];
+
+  static Entity? spawn(
+    int objId,
+    double x,
+    double y,
+    int difficultyLevel,
+    int maxSprites,
+  ) {
+    for (final spawner in _spawners) {
+      Entity? entity = spawner(objId, x, y, difficultyLevel);
+
+      if (entity != null) {
+        // Safety bounds check for the VSWAP array
+        if (entity.spriteIndex >= 0 && entity.spriteIndex < maxSprites) {
+          return entity;
+        }
+        return null; // VSWAP doesn't have this sprite!
+      }
+    }
+    return null; // No class claimed this Map ID
+  }
+}