Add dynamic UART/BLE host connect for serve, dashboard, and WS.

Serve starts without a required port; REST/WS/UI can scan and switch transports, with BLE live ticks and UART-only OTA.

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

goTool/api_serve.go

@@ -93,6 +93,7 @@ type otaAPIResponse struct {
 }
 
 func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub, streamCtl *accelStreamCtl, tapCtl *tapNotifyCtl) {
+	mountHostAPI(mux, link)
 	mountLiveStreamAPI(mux, hub)
 	mountAccelStreamAPI(mux, link, hub, streamCtl)
 	mountTapAPI(mux, link, hub, tapCtl)
@@ -157,6 +158,10 @@ func mountServeAPI(mux *http.ServeMux, link *managedSerial, hub *wsHub, streamCt
 }
 
 func serveOTAUpload(w http.ResponseWriter, r *http.Request, link *managedSerial, hub *wsHub) {
+	if link.Transport() != hostTransportUART || !link.IsConnected() {
+		writeJSON(w, http.StatusBadRequest, otaAPIResponse{Error: "OTA requires UART host (DIP8=0)"})
+		return
+	}
 	if err := r.ParseMultipartForm(otaMaxFirmwareSize); err != nil {
 		writeJSON(w, http.StatusBadRequest, otaAPIResponse{Error: "invalid form"})
 		return