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/Services/GachaPointService.cs

@@ -210,9 +210,7 @@ public sealed class GachaPointService : IGachaPointService
         // Emblem (standard legendary) or Skin+Emblem (leader). Convert at the wire boundary
         // so ExchangeOutcome still carries RewardListEntry for the controller response.
         var granted = await tx.GrantAsync(UserGoodsType.Card, cardId, 1);
-        var rewardList = granted
-            .Select(g => new RewardListEntry { RewardType = g.RewardType, RewardId = g.RewardId, RewardNum = g.RewardNum })
-            .ToList();
+        var rewardList = granted.ToRewardList();
 
         return ExchangeOutcome.Ok(rewardList);
     }