fix(unity): resolve all 32 C# compilation errors

- CardModel: add missing `id` field
- CardModel: `imageUrl` → `imageUri` (match JSON property name)
- DeckModel: `commanderName` → `commander` (match JSON property name)
- PreconDeck: `imageUrl` → `imageUri`
- Add missing `PreconListWrapper` model class
- Add `using UnityEngine.Networking` to CollectionController,
  DeckGeneratorController, PreconController
- Remove double StartCoroutine() wrapping on ApiClient calls
  (GetRaw/PatchRaw/Delete/PostRaw already return Coroutine)
  Affected: CollectionController, DeckBuilderController,
  DeckGeneratorController, ScannerController, CoachController

unity-client/Assets/Scripts/UI/ScannerController.cs

@@ -292,8 +292,8 @@ namespace CommanderAILab.UI
             resultSet.text = card.set;
             resultOracleText.text = card.oracleText;
             resultConfidence.text = $"Confidence: {confidence:P0}";
-            if (!string.IsNullOrEmpty(card.imageUrl))
-                ImageCache.Instance.GetSprite(card.imageUrl, s => { if (resultCardImage != null) resultCardImage.sprite = s; });
+            if (!string.IsNullOrEmpty(card.imageUri))
+                ImageCache.Instance.GetSprite(card.imageUri, s => { if (resultCardImage != null) resultCardImage.sprite = s; });
             AddToHistory(card);
         }
 
@@ -320,9 +320,9 @@ namespace CommanderAILab.UI
         {
             if (_scannedCard == null) return;
             var body = JsonConvert.SerializeObject(new { card_id = _scannedCard.id, qty = 1 });
-            StartCoroutine(ApiClient.Instance.PostRaw("/api/collection/add", body,
+            ApiClient.Instance.PostRaw("/api/collection/add", body,
                 _ => cameraStatusText.text = $"Added {_scannedCard.name} to collection",
-                err => ShowError($"Add to collection failed:\n{err}")));
+                err => ShowError($"Add to collection failed:\n{err}"));
         }
 
         private void OnAddToDeck()