Fix web OTA upload and isolate OTA sessions across firmware and goTool.

Split ESP-NOW into core/master/slave modules, block non-OTA UART traffic during updates, and hold the host serial port exclusively so dashboard polling cannot interleave with firmware uploads.

Co-authored-by: Cursor <cursoragent@cursor.com>

goTool/cmd_ota.go

@@ -16,8 +16,7 @@ func runOTA(sp *serialPort, args []string) error {
 
 	sp.mu.Lock()
 	defer sp.mu.Unlock()
-	m := &managedSerial{quiet: false, sp: sp}
-	return runOTAOnPortUnlocked(m, data, func(p OTAProgress) {
+	return runOTAOnPortUnlocked(sp, data, func(p OTAProgress) {
 		switch p.Phase {
 		case "preparing", "ready":
 			fmt.Println(p.Message)