The vlessenc fix (#5185) enabled flow on XHTTP only in the security=none
branch of genVlessLink, and the Clash builder still gated flow on
network==tcp. With XHTTP+REALITY+vlessenc the panel accepts and stores
the flow (inboundCanEnableTlsFlow passes), but subscriptions dropped it,
so clients received configs without xtls-rprx-vision.
Add vlessFlowAllowed mirroring inboundCanEnableTlsFlow — tcp with
tls/reality, or xhttp with vlessenc regardless of security layer — and
use it in both the vless:// link generator and the Clash proxy builder.
MHSanaei