refactor: type reward_type columns as UserGoodsType enum

Replace bare `int RewardType` on 12 catalog/reward entities and GrantedReward
with the existing UserGoodsType enum. Verified against the decompiled client:
every wire reward_type decodes through the single Wizard.UserGoods.Type enum, so
one enum is correct across all endpoint families (item_type is a separate
Item.Type axis, left untouched). EF stores the enum as the same int column, so
there is no migration.

- Importers cast seed int -> UserGoodsType at the ingest boundary.
- New GrantedReward.ToRewardList() extension replaces 8 copy-pasted
  GrantedReward -> RewardListEntry projections.
- Fix 3 .ToString() sites that would otherwise emit enum names ("Crystal")
  instead of the int wire value ("2").
- Wire DTOs keep int; the enum is widened to int at the wire boundary only.

Build green; 962/962 tests pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Controllers/SleeveController.cs

@@ -68,7 +68,7 @@ public class SleeveController : SVSimController
                     IsPurchasedProduct = IsProductPurchased(p, ownedSleeveIds),
                     Rewards = p.Rewards.OrderBy(r => r.OrderIndex).Select(r => new SleeveProductRewardDto
                     {
-                        RewardType = r.RewardType,
+                        RewardType = (int)r.RewardType,
                         RewardDetailId = r.RewardDetailId,
                         RewardNumber = r.RewardNumber,
                     }).ToList(),
@@ -142,15 +142,13 @@ public class SleeveController : SVSimController
 
         // Grant each catalog reward through the central dispatcher.
         foreach (var r in product.Rewards.OrderBy(r => r.OrderIndex))
-            await tx.GrantAsync((UserGoodsType)r.RewardType, r.RewardDetailId, r.RewardNumber);
+            await tx.GrantAsync(r.RewardType, r.RewardDetailId, r.RewardNumber);
 
         var result = await tx.CommitAsync(HttpContext.RequestAborted);
 
         return new SleeveBuyResponse
         {
-            RewardList = result.RewardList
-                .Select(g => new RewardListEntry { RewardType = g.RewardType, RewardId = g.RewardId, RewardNum = g.RewardNum })
-                .ToList(),
+            RewardList = result.RewardList.ToRewardList(),
         };
     }
 
@@ -164,7 +162,7 @@ public class SleeveController : SVSimController
     {
         foreach (var r in product.Rewards)
         {
-            if (r.RewardType == (int)UserGoodsType.Sleeve && ownedSleeveIds.Contains(r.RewardDetailId))
+            if (r.RewardType == UserGoodsType.Sleeve && ownedSleeveIds.Contains(r.RewardDetailId))
                 return true;
         }
         return false;