Implement Fort Fight minigame (#75)

Co-authored-by: Michal Pikulski <michal.a.pikulski@gmail.com>
Reviewed-on: #75

Assets/Scripts/Minigames/FortFight/Projectiles/TrashPiece.cs

@@ -0,0 +1,84 @@
+using Core;
+using UnityEngine;
+
+namespace Minigames.FortFight.Projectiles
+{
+    /// <summary>
+    /// Component for individual trash pieces spawned by TrashBagProjectile.
+    /// Deals pre-configured damage on collision with blocks, spawns impact effect, then auto-cleans up after timeout.
+    /// </summary>
+    public class TrashPiece : MonoBehaviour
+    {
+        [Header("Visual Effects")]
+        [Tooltip("Impact effect prefab spawned on block collision")]
+        [SerializeField] private GameObject impactEffectPrefab;
+        
+        private float damage;
+        private bool hasHit = false;
+        
+        private void Start()
+        {
+            // Get configuration from settings
+            var settings = GameManager.GetSettingsObject<AppleHills.Core.Settings.IFortFightSettings>();
+            damage = settings?.TrashPieceDamage ?? 5f;
+            float lifetime = settings?.TrashPieceLifetime ?? 5f;
+            
+            // Auto-cleanup after configured timeout
+            Destroy(gameObject, lifetime);
+        }
+        
+        private void OnCollisionEnter2D(Collision2D collision)
+        {
+            if (hasHit) return;
+            
+            // Check if hit a fort block
+            var block = collision.gameObject.GetComponent<Fort.FortBlock>();
+            if (block != null)
+            {
+                hasHit = true;
+                
+                // Deal damage
+                block.TakeDamage(damage);
+                Logging.Debug($"[TrashPiece] Dealt {damage} damage to {block.gameObject.name}");
+                
+                // Spawn impact effect at collision point
+                if (impactEffectPrefab != null && collision.contacts.Length > 0)
+                {
+                    Vector2 impactPoint = collision.contacts[0].point;
+                    GameObject effect = Instantiate(impactEffectPrefab, impactPoint, Quaternion.identity);
+                    
+                    // Dynamically determine cleanup time from particle system
+                    float lifetime = GetEffectLifetime(effect);
+                    Destroy(effect, lifetime);
+                }
+                
+                // Destroy trash piece immediately after dealing damage
+                Destroy(gameObject);
+            }
+        }
+        
+        /// <summary>
+        /// Get the lifetime of an effect by reading particle system StartLifetime.
+        /// Falls back to 2 seconds if no particle system found.
+        /// </summary>
+        private float GetEffectLifetime(GameObject effect)
+        {
+            // Try to read from ParticleSystem
+            ParticleSystem ps = effect.GetComponent<ParticleSystem>();
+            if (ps != null)
+            {
+                return ps.main.startLifetime.constantMax + 0.5f; // Add small buffer
+            }
+            
+            // Try to read from child particle systems
+            ParticleSystem childPs = effect.GetComponentInChildren<ParticleSystem>();
+            if (childPs != null)
+            {
+                return childPs.main.startLifetime.constantMax + 0.5f;
+            }
+            
+            // Fallback for non-particle effects
+            return 2f;
+        }
+    }
+}