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/AchievementController.cs

@@ -72,7 +72,7 @@ public class AchievementController : SVSimController
         await using var tx = await _inv.BeginAsync(viewerId, ct);
 
         var granted = await tx.GrantAsync(
-            (UserGoodsType)catalogRow.RewardType,
+            catalogRow.RewardType,
             catalogRow.RewardDetailId,
             catalogRow.RewardNumber,
             ct);
@@ -108,13 +108,13 @@ public class AchievementController : SVSimController
             MissionReceiveType = dto.MissionReceiveType,
             RewardList = granted.Select(g => new RewardGrantDto
             {
-                RewardType = g.RewardType,
+                RewardType = (int)g.RewardType,
                 RewardId = g.RewardId,
                 RewardNum = g.RewardNum,
             }).ToList(),
             TotalReceiveCountList = granted.Select(g => new TotalReceiveCountDto
             {
-                RewardType = g.RewardType,
+                RewardType = (int)g.RewardType,
                 RewardDetailId = g.RewardId,
                 RewardCount = g.RewardNum,
                 ItemType = 0,