Switch to IPv4 zeroconf, add test framework with discovery test, fix serial enumeration

lib/client/serial.go

@@ -3,6 +3,7 @@ package client
 import (
 	"fmt"
 	"io"
+	"strings"
 	"time"
 
 	"go.bug.st/serial"
@@ -16,7 +17,7 @@ func ListSerial() ([]string, error) {
 	}
 	var result []string
 	for _, p := range ports {
-		if p.IsUSB {
+		if p.IsUSB && p.VID == "2E8A" && strings.HasPrefix(p.Name, "/dev/cu.") {
 			result = append(result, p.Name)
 		}
 	}