core/types: fix CopyHeader missing BlockAccessListHash deep copy

CopyHeader copies all pointer-typed header fields (WithdrawalsHash,
RequestsHash, SlotNumber, etc.) but was missing the deep copy for
BlockAccessListHash added by EIP-7928. This caused the BAL hash
to be silently shared between the original and the copy, leading
to potential data races and incorrect nil-checks on copied headers.

Author: CPerezz

core/types/block.go

@@ -333,6 +333,10 @@ func CopyHeader(h *Header) *Header {
 		cpy.RequestsHash = new(common.Hash)
 		*cpy.RequestsHash = *h.RequestsHash
 	}
+	if h.BlockAccessListHash != nil {
+		cpy.BlockAccessListHash = new(common.Hash)
+		*cpy.BlockAccessListHash = *h.BlockAccessListHash
+	}
 	if h.SlotNumber != nil {
 		cpy.SlotNumber = new(uint64)
 		*cpy.SlotNumber = *h.SlotNumber