fix: decode payload transactions with EIP-2718 exact format (#219)

Engine API specifies transactions as opaque EIP-2718 encoded bytes, not
devp2p wire format. Using network_decode here could silently drop typed
transactions (EIP-1559, EIP-2930, EvNode 0x76/0x78) whose bytes are
valid EIP-2718 but lack the wire-format RLP string wrapping.

The executor already uses decode_2718_exact when validating the same
transactions via ExecutionData. This aligns the payload builder with
executor semantics, closing a potential consensus mismatch where
build-time acceptance diverges from validation-time rules.

Author: randygrok

crates/node/src/payload_service.rs

@@ -223,7 +223,7 @@ where
                 .unwrap_or_default()
                 .into_iter()
                 .filter_map(|tx_bytes| {
-                    match TransactionSigned::network_decode(&mut tx_bytes.as_ref()) {
+                    match TransactionSigned::decode_2718_exact(tx_bytes.as_ref()) {
                         Ok(tx) => Some(tx),
                         Err(err) => {
                             tracing::warn!(