fix: owned items showed a price because they were served as base avatar items

defaultbaseavataritems returned the first 100 catalog items. The 2023
client flags every row of that list as a custom-clothing template
(AvatarItemData.IsBaseAvatarItem, keyed by AvatarItemId) and skips
templates when it rebuilds the owned outfit-menu entries, so those 100
ordinary items (80sHipHopJacket, Beard Close, ...) showed a price even
when owned and equipped, while the cart (which checks the owned set)
said "owned".

- defaultbaseavataritems returns only the UGC templates, UGCTee_Shirt
  (AvatarItemId 2184) and UGCPulloverHoodie_Shirt (2918), as the real
  service served them
- those two keep the same ids in every list and carry IsBaseAvatarItem
- they're no longer sold (existing shop rows are removed on seed) or
  listed as owned clothing

DorkNet.Server/Services/StoreService.cs

@@ -179,7 +179,11 @@ public class StoreService(DorkNetDbContext db, LevelService level, IConfiguratio
             foreach (var row in stale)
             {
                 var guid = row.Slug.Substring("wardrobe-".Length);
-                if (!safe.Contains(guid)) toDelete.Add(row.Id);
+                // Custom-clothing templates aren't sold; drop rows seeded
+                // before they were excluded.
+                if (!safe.Contains(guid) ||
+                    DorkNet.Server.Controllers.API.Avatar.V4.AvatarItemsController.IsBaseAvatarItemGuid(guid))
+                    toDelete.Add(row.Id);
             }
             if (toDelete.Count > 0)
             {
@@ -690,6 +694,9 @@ public class StoreService(DorkNetDbContext db, LevelService level, IConfiguratio
         var added = false;
         foreach (var (guid, dto) in catalog)
         {
+            // The UGC templates are the base of custom clothing, not shop
+            // items (the real store never listed them).
+            if (dto.IsBaseAvatarItem) continue;
             var slug = $"wardrobe-{guid}";
             if (existingSlugs.Contains(slug)) continue;
             existingSlugs.Add(slug);