add csfloat api usage

BlueLaminate/BlueLaminate.EFCore/Configurations/SkinInstanceConfiguration.cs

@@ -8,19 +8,34 @@ public class SkinInstanceConfiguration : IEntityTypeConfiguration<SkinInstance>
 {
     public void Configure(EntityTypeBuilder<SkinInstance> entity)
     {
-        entity.Property(e => e.FloatValue).HasColumnType("numeric(10,9)");
+        // Full precision so exact-match dupe detection isn't defeated by rounding.
+        // CSFloat returns deterministic ~17-digit floats; numeric(20,18) holds them.
+        entity.Property(e => e.FloatValue).HasColumnType("numeric(20,18)");
 
-        // Primary lookup key for trade fingerprinting.
-        entity.HasIndex(e => e.FloatValue);
-        entity.HasIndex(e => e.PaintSeed);
+        // The fingerprint that identifies a physical item. NOT unique: duped items
+        // legitimately share a fingerprint, and detecting that collision is the
+        // point. Indexed for fast fingerprint resolution during the sweep.
+        entity.HasIndex(e => new
+        {
+            e.SkinId,
+            e.FloatValue,
+            e.PaintSeed,
+            e.StatTrak,
+            e.Souvenir,
+        });
+
+        // Surfacing fresh dupes is a hot query.
+        entity.HasIndex(e => e.SuspectedDupe);
 
         entity.HasOne(e => e.Skin)
             .WithMany(s => s.Instances)
             .HasForeignKey(e => e.SkinId);
 
+        // Condition is optional now (derived from float later); set null on delete
+        // rather than restrict so condition rows can change without blocking.
         entity.HasOne(e => e.Condition)
             .WithMany(c => c.Instances)
             .HasForeignKey(e => e.ConditionId)
-            .OnDelete(DeleteBehavior.Restrict);
+            .OnDelete(DeleteBehavior.SetNull);
     }
 }