Remove USB/serial support: network-only protocol, drop tinyusb and PICOBOOT

lib/client/client.go

@@ -100,11 +100,6 @@ func first[T any](results []Response[T], err error) (*T, error) {
 	return results[0].Value, nil
 }
 
-func (c *Client) PICOBOOT() error {
-	_, err := first(roundTrip[ResponsePICOBOOT](c, &RequestPICOBOOT{}))
-	return err
-}
-
 func (c *Client) Info() (*ResponseInfo, error) {
 	return first(roundTrip[ResponseInfo](c, &RequestInfo{}))
 }