feat(#143): add CommanderZoneWidget with art crop, cast counter, and tax display

unity-client/Assets/Scripts/UI/Battleground/CommanderZoneWidget.cs

@@ -0,0 +1,69 @@
+using UnityEngine;
+using UnityEngine.UI;
+using TMPro;
+using CommanderAILab.Models;
+using CommanderAILab.Services;
+
+namespace CommanderAILab.UI
+{
+    /// <summary>
+    /// Per-seat commander zone widget.
+    /// Shows: art crop banner, commander name, cast count, commander tax.
+    /// Requires ImageCache singleton in scene.
+    /// </summary>
+    public class CommanderZoneWidget : MonoBehaviour
+    {
+        [Header("References")]
+        [SerializeField] private RawImage   artCropImage;
+        [SerializeField] private TMP_Text   commanderNameLabel;
+        [SerializeField] private TMP_Text   castCountLabel;
+        [SerializeField] private TMP_Text   taxLabel;
+        [SerializeField] private UnityEngine.UI.Button castCommanderBtn;
+
+        public CardModel CommanderCard { get; private set; }
+        private int _castCount = 0;
+
+        // ── Binding ───────────────────────────────────────────
+        public void Bind(CardModel commander)
+        {
+            CommanderCard = commander;
+            _castCount    = commander != null ? commander.counters.GetValueOrDefault("cast_count", 0) : 0;
+
+            if (commanderNameLabel)
+                commanderNameLabel.text = commander?.name ?? "No Commander";
+
+            UpdateTaxDisplay();
+
+            // Load art crop from Scryfall
+            if (commander != null && !string.IsNullOrEmpty(commander.name)
+                && artCropImage != null && ImageCache.Instance != null)
+            {
+                StartCoroutine(ImageCache.Instance.LoadArtCrop(commander.name, artCropImage));
+            }
+        }
+
+        // ── Cast tracking ──────────────────────────────────────
+        public void OnCommanderCast()
+        {
+            _castCount++;
+            UpdateTaxDisplay();
+        }
+
+        public void SetCastCount(int count)
+        {
+            _castCount = Mathf.Max(0, count);
+            UpdateTaxDisplay();
+        }
+
+        // ── Internal ──────────────────────────────────────────
+        private void UpdateTaxDisplay()
+        {
+            if (castCountLabel)
+                castCountLabel.text = _castCount == 0 ? "Not yet cast" : $"Cast #{_castCount}";
+
+            int tax = _castCount * 2;
+            if (taxLabel)
+                taxLabel.text = tax == 0 ? "No tax" : $"+{tax} ☀ tax";
+        }
+    }
+}