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.Database/Models/BattlePassRewardEntry.cs

@@ -13,7 +13,7 @@ public class BattlePassRewardEntry : BaseEntity<long>
     public int SeasonId { get; set; }
     public BattlePassTrack Track { get; set; }
     public int Level { get; set; }
-    public int RewardType { get; set; }
+    public UserGoodsType RewardType { get; set; }
     public long RewardDetailId { get; set; }
     public int RewardNumber { get; set; }
     public bool IsAppealExclusion { get; set; }