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

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

lib/features/entities/enemies/enemy.dart

@@ -0,0 +1,79 @@
+import 'dart:math' as math;
+
+import 'package:wolf_dart/classes/linear_coordinates.dart';
+import 'package:wolf_dart/features/entities/entity.dart';
+
+abstract class Enemy extends Entity {
+  Enemy({
+    required super.x,
+    required super.y,
+    required super.spriteIndex,
+    super.angle,
+    super.state,
+    super.mapId,
+    super.lastActionTime,
+  });
+
+  // Decodes the Map ID to figure out which way the enemy is facing
+  static double getInitialAngle(int objId) {
+    int normalizedId = (objId - 108) % 36;
+    int direction = normalizedId % 4; // 0=East, 1=North, 2=West, 3=South
+
+    switch (direction) {
+      case 0:
+        return 0.0;
+      case 1:
+        return 3 * math.pi / 2;
+      case 2:
+        return math.pi;
+      case 3:
+        return math.pi / 2;
+      default:
+        return 0.0;
+    }
+  }
+
+  // The enemy can now check its own line of sight!
+  bool hasLineOfSight(
+    LinearCoordinates player,
+    bool Function(int x, int y) isWalkable,
+  ) {
+    double dx = player.x - x;
+    double dy = player.y - y;
+    double distance = math.sqrt(dx * dx + dy * dy);
+
+    // 1. FOV Check
+    double angleToPlayer = math.atan2(dy, dx);
+    double diff = angle - angleToPlayer;
+
+    while (diff <= -math.pi) {
+      diff += 2 * math.pi;
+    }
+    while (diff > math.pi) {
+      diff -= 2 * math.pi;
+    }
+
+    if (diff.abs() > math.pi / 2) return false;
+
+    // 2. Map Check
+    double dirX = dx / distance;
+    double dirY = dy / distance;
+    double stepSize = 0.2;
+    for (double i = 0; i < distance; i += stepSize) {
+      int checkX = (x + dirX * i).toInt();
+      int checkY = (y + dirY * i).toInt();
+
+      if (!isWalkable(checkX, checkY)) return false;
+    }
+
+    return true;
+  }
+
+  // Update signature is cleaner now
+  void update({
+    required int elapsedMs,
+    required LinearCoordinates player,
+    required bool Function(int x, int y) isWalkable,
+    required void Function(int damage) onDamagePlayer,
+  });
+}