Refactor to consolidate APIs into contract package and introduce NFT interface for better modularity and maintainability.

version.go

@@ -1,21 +1,14 @@
 package nft
 
-type Version interface {
-	// Version returns the version of the nftables client.
-	Version() string
-	// Opts returns the options of the nftables client.
-	Opts() map[string]string
-}
-
 type version struct {
 	version string
 	opts    map[string]string
 }
 
-func (v version) Version() string {
+func (v *version) Version() string {
 	return v.version
 }
 
-func (v version) Opts() map[string]string {
+func (v *version) Opts() map[string]string {
 	return v.opts
 }