Ensure enemies only lock onto player once they have line of sight

src/rendering/DungeonRenderer.ts

@@ -324,4 +324,8 @@ export class DungeonRenderer {
   showLevelUp(x: number, y: number) {
     this.fxRenderer.showLevelUp(x, y);
   }
+
+  showAlert(x: number, y: number) {
+    this.fxRenderer.showAlert(x, y);
+  }
 }

src/rendering/FxRenderer.ts

@@ -188,4 +188,35 @@ export class FxRenderer {
       onComplete: () => text.destroy()
     });
   }
+
+  showAlert(x: number, y: number) {
+    const screenX = x * TILE_SIZE + TILE_SIZE / 2;
+    const screenY = y * TILE_SIZE - 8;
+
+    const text = this.scene.add.text(screenX, screenY, "!", {
+      fontSize: "24px",
+      color: "#ffaa00",
+      stroke: "#000",
+      strokeThickness: 3,
+      fontStyle: "bold"
+    }).setOrigin(0.5, 1).setDepth(210);
+
+    // Exclamation mark stays visible for alert duration
+    this.scene.tweens.add({
+      targets: text,
+      y: screenY - 8,
+      duration: 200,
+      yoyo: true,
+      repeat: 3, // Bounce a few times
+      ease: "Sine.inOut"
+    });
+
+    this.scene.tweens.add({
+      targets: text,
+      alpha: 0,
+      delay: 900, // Start fading out near end of alert period
+      duration: 300,
+      onComplete: () => text.destroy()
+    });
+  }
 }