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/BuildDeckController.cs

@@ -94,7 +94,7 @@ public class BuildDeckController : SVSimController
                 .OrderBy(r => r.RewardIndex)
                 .Select(r => new BuildDeckProductRewardDto
                 {
-                    RewardType = r.RewardType,
+                    RewardType = (int)r.RewardType,
                     RewardDetailId = r.RewardDetailId,
                     RewardNumber = r.RewardNumber,
                     MessageId = r.MessageId,
@@ -120,7 +120,7 @@ public class BuildDeckController : SVSimController
                 IsGet = totalSeriesPurchases >= g.Key,
                 RewardList = g.OrderBy(r => r.ItemIndex).Select(r => new BuildDeckProductRewardDto
                 {
-                    RewardType = r.RewardType,
+                    RewardType = (int)r.RewardType,
                     RewardDetailId = r.RewardDetailId,
                     RewardNumber = r.RewardNumber,
                     MessageId = r.MessageId,
@@ -206,7 +206,7 @@ public class BuildDeckController : SVSimController
 
         // Per-buy rewards
         foreach (var r in product.Rewards.OrderBy(r => r.RewardIndex))
-            await tx.GrantAsync((UserGoodsType)r.RewardType, r.RewardDetailId, r.RewardNumber);
+            await tx.GrantAsync(r.RewardType, r.RewardDetailId, r.RewardNumber);
 
         // Series-reward tier crossings
         var crossedTiers = product.Series.SeriesRewards
@@ -220,10 +220,10 @@ public class BuildDeckController : SVSimController
         {
             foreach (var item in tier.OrderBy(r => r.ItemIndex))
             {
-                await tx.GrantAsync((UserGoodsType)item.RewardType, item.RewardDetailId, item.RewardNumber);
+                await tx.GrantAsync(item.RewardType, item.RewardDetailId, item.RewardNumber);
                 seriesRewards.Add(new BuildDeckProductRewardDto
                 {
-                    RewardType = item.RewardType,
+                    RewardType = (int)item.RewardType,
                     RewardDetailId = item.RewardDetailId,
                     RewardNumber = item.RewardNumber,
                     MessageId = item.MessageId,
@@ -235,9 +235,7 @@ public class BuildDeckController : SVSimController
 
         return new BuildDeckBuyResponse
         {
-            RewardList = result.RewardList
-                .Select(g => new RewardListEntry { RewardType = g.RewardType, RewardId = g.RewardId, RewardNum = g.RewardNum })
-                .ToList(),
+            RewardList = result.RewardList.ToRewardList(),
             SeriesRewards = seriesRewards,
         };
     }