The bot's add-client flow already serialised client_Flow into the VLESS
JSON template but never exposed a way to set it from Telegram, so every
client ended up with an empty flow regardless of the inbound's transport.
Added an inline "Flow" row to the VLESS protocol keyboard with three
choices — None, xtls-rprx-vision, and xtls-rprx-vision-udp443 — and a
matching i18n key in all 13 locale files. The row is only shown when
the inbound can actually use Vision flow (mirrors the frontend's
canEnableTlsFlow check: VLESS over TCP with TLS or Reality); on other
transports it's hidden and any stale client_Flow value is reset, so the
generated JSON stays consistent with the inbound's stream settings.