Add per-slave ESP-NOW OTA progress over UART and fix dashboard updates.

Expose OTA_SLAVE_PROGRESS on the master, track per-slave state during
distribution, run ESP-NOW OTA in a background task so the host can poll
while slaves update, and show master/slave progress in the dashboard
with table layout and faster WebSocket refresh during uploads.

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

goTool/client_api.go

@@ -16,6 +16,14 @@ func (m *managedSerial) getVersion() (*pb.VersionResponse, error) {
 	return decodeVersionPayload(payload)
 }
 
+func (m *managedSerial) getVersionPoll() (*pb.VersionResponse, error) {
+	payload, err := m.exchangePoll(byte(pb.MessageType_VERSION), "VERSION")
+	if err != nil {
+		return nil, err
+	}
+	return decodeVersionPayload(payload)
+}
+
 func (m *managedSerial) listClients() ([]*pb.ClientInfo, error) {
 	payload, err := m.exchange(byte(pb.MessageType_CLIENT_INFO), "CLIENT_INFO")
 	if err != nil {
@@ -24,9 +32,28 @@ func (m *managedSerial) listClients() ([]*pb.ClientInfo, error) {
 	return decodeClientsPayload(payload)
 }
 
+func (m *managedSerial) listClientsPoll() ([]*pb.ClientInfo, error) {
+	payload, err := m.exchangePoll(byte(pb.MessageType_CLIENT_INFO), "CLIENT_INFO")
+	if err != nil {
+		return nil, err
+	}
+	return decodeClientsPayload(payload)
+}
+
 func (m *managedSerial) AccelDeadzone(req *pb.AccelDeadzoneRequest) (*pb.AccelDeadzoneResponse, error) {
+	return m.accelDeadzoneVia(m.withPort, req)
+}
+
+func (m *managedSerial) AccelDeadzonePoll(req *pb.AccelDeadzoneRequest) (*pb.AccelDeadzoneResponse, error) {
+	return m.accelDeadzoneVia(m.withPortPoll, req)
+}
+
+func (m *managedSerial) accelDeadzoneVia(
+	portFn func(func(*serialPort) error) error,
+	req *pb.AccelDeadzoneRequest,
+) (*pb.AccelDeadzoneResponse, error) {
 	var resp *pb.AccelDeadzoneResponse
-	err := m.withPort(func(sp *serialPort) error {
+	err := portFn(func(sp *serialPort) error {
 		var e error
 		resp, e = sp.AccelDeadzone(req)
 		return e