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/PackController.cs

@@ -418,9 +418,7 @@ public class PackController : SVSimController
         // CommitAsync saves all mutations and produces reward_list with currency-collision resolved.
         // Tutorial path never calls TrySpendAsync so no currency op is in the log — correct.
         var result = await tx.CommitAsync(HttpContext.RequestAborted);
-        var rewardList = result.RewardList
-            .Select(g => new RewardListEntry { RewardType = g.RewardType, RewardId = g.RewardId, RewardNum = g.RewardNum })
-            .ToList();
+        var rewardList = result.RewardList.ToRewardList();
 
         return new PackOpenResponse
         {