add csfloat api usage

BlueLaminate/BlueLaminate.EFCore/Configurations/SkinConfiguration.cs

@@ -21,6 +21,18 @@ public class SkinConfiguration : IEntityTypeConfiguration<Skin>
         // Slug is the natural key the sync upserts against.
         entity.HasIndex(e => e.Slug).IsUnique();
 
+        // Market listings join back to a skin by (def_index, paint_index). Unique
+        // among populated rows; filtered so the many catalogue rows that predate
+        // these columns (null) don't collide. Postgres treats nulls as distinct
+        // anyway, but the filter makes the intent explicit and the index smaller.
+        entity.HasIndex(e => new { e.DefIndex, e.PaintIndex })
+            .IsUnique()
+            .HasFilter("def_index IS NOT NULL AND paint_index IS NOT NULL");
+
+        // The catalogue sweep orders skins by when they were last swept (nulls
+        // first) to resume across capped runs; index that ordering.
+        entity.HasIndex(e => e.ListingsSweptAt);
+
         entity.HasOne(e => e.Weapon)
             .WithMany(w => w.Skins)
             .HasForeignKey(e => e.WeaponId);