add missing pokedex offset spoof for gen3 saves

https://projectpokemon.org/home/forums/topic/55704-drag-drop-to-boxes-not-working-in-blank-gen-3-save/
ty ICanSnake

PKHeX.Core/Saves/SAV3.cs

@@ -94,6 +94,7 @@ namespace PKHeX.Core
                 GameVersion.E => Legal.Pouch_Key_E,
                 _ => Legal.Pouch_Key_FRLG
             };
+            PokeDex = BlockOfs[0] + 0x18;
             SeenFlagOffsets = Array.Empty<int>();
 
             Initialize();