added inventory and stamina system

Assets/Scripts/StaminaBoostPickup.cs

@@ -0,0 +1,36 @@
+using UnityEngine;
+
+/// <summary>
+/// Add to a pickup GameObject alongside PickupItem.
+/// When the item is collected, applies a one-time boost to the player's max stamina.
+/// </summary>
+[RequireComponent(typeof(PickupItem))]
+public class StaminaBoostPickup : MonoBehaviour
+{
+    [Tooltip("Max stamina will be set to this value when picked up.")]
+    public float newMaxStamina = 200f;
+
+    void Start()
+    {
+        // Hook into PickupItem's collect event via a simple poll
+        var pickup = GetComponent<PickupItem>();
+        // We override by watching PickupItem's collected state each frame
+        StartCoroutine(WatchForCollect(pickup));
+    }
+
+    System.Collections.IEnumerator WatchForCollect(PickupItem pickup)
+    {
+        // Wait until the pickup is destroyed (collected)
+        while (pickup != null)
+            yield return null;
+
+        // Find player and apply boost
+        Player p = FindObjectOfType<Player>();
+        if (p != null)
+        {
+            p.maxStamina = newMaxStamina;
+            p.stamina    = newMaxStamina;
+            Debug.Log($"[StaminaBoost] Max stamina set to {newMaxStamina}");
+        }
+    }
+}