Delete what the cut left behind

tail() read the id out of a subtree route and no route is a subtree any more;
lxrDecodeBytes32 and lxrPadBytes served the V4 router builders that went with
the precompile answering 0x. staticcheck is clean on pkg/gateway and
cmd/gateway.

Co-authored-by: Hanzo Dev <[email protected]>

pkg/gateway/abi.go

@@ -40,23 +40,6 @@ func lxrDecodeAddress(s string) ([20]byte, error) {
 	return addr, nil
 }
 
-// lxrDecodeBytes32 parses a 0x-prefixed hex string into a 32-byte array.
-func lxrDecodeBytes32(s string) ([32]byte, error) {
-	var out [32]byte
-	s = strings.TrimPrefix(s, "0x")
-	if len(s) > 64 {
-		return out, fmt.Errorf("bytes32 too long: %d hex chars", len(s))
-	}
-	// Left-pad with zeros if shorter than 64 hex chars.
-	s = strings.Repeat("0", 64-len(s)) + s
-	b, err := hex.DecodeString(s)
-	if err != nil {
-		return out, fmt.Errorf("invalid hex: %w", err)
-	}
-	copy(out[:], b)
-	return out, nil
-}
-
 // lxrPadAddress left-pads a 20-byte address to 32 bytes (EVM ABI word).
 func lxrPadAddress(addr [20]byte) []byte {
 	var word [32]byte
@@ -78,13 +61,6 @@ func lxrPadUint256(n *big.Int) []byte {
 	return word[:]
 }
 
-// lxrPadBytes pads arbitrary bytes to the next 32-byte boundary.
-func lxrPadBytes(b []byte) []byte {
-	padded := make([]byte, ((len(b)+31)/32)*32)
-	copy(padded, b)
-	return padded
-}
-
 // lxrMustDecodeHex decodes a hex string, panicking on error (init-time only).
 func lxrMustDecodeHex(s string) []byte {
 	b, err := hex.DecodeString(s)

pkg/gateway/server.go

@@ -9,7 +9,6 @@ import (
 	"net/http"
 	"sort"
 	"strconv"
-	"strings"
 	"time"
 
 	"github.com/google/uuid"
@@ -146,14 +145,6 @@ func (s *Server) Shutdown(ctx context.Context) error {
 // One namespace, one owner, one document.
 const tradePrefix = "/v1/trade"
 
-// tail is what a subtree route was asked about — the pool id, the order id.
-// It reads the same constant the route was mounted from, because a route
-// registered from the prefix and parsed from a copy of it is one rename away
-// from every id arriving with a path stuck to the front of it.
-func tail(r *http.Request, route string) string {
-	return strings.TrimPrefix(r.URL.Path, tradePrefix+route)
-}
-
 // routes is the surface, once. api/openapi.yaml describes exactly this, and a
 // test holds the two to each other — a route added here and not written down
 // is a route no client can be told about, and a path written down and not