feat(netlink): detect IPv6 using query to address

- If a default IPv6 route is found, query the ip:port defined by `IPV6_CHECK_ADDRESS` to check for internet access

internal/netlink/interfaces.go

@@ -1,9 +1,19 @@
 package netlink
 
-import "github.com/qdm12/log"
+import (
+	"context"
+	"net/netip"
+
+	"github.com/qdm12/log"
+)
 
 type DebugLogger interface {
 	Debug(message string)
 	Debugf(format string, args ...any)
 	Patch(options ...log.Option)
 }
+
+type Firewall interface {
+	AcceptOutput(ctx context.Context, protocol, intf string, ip netip.Addr,
+		port uint16, remove bool) (err error)
+}