fix(tgbot): close stale-inbound TOCTOU and contain handler panics (#6442)

Tapping an old get_clients_for_* inline keyboard re-fetched the inbound
after the keyboard lookup, discarding the error; if the row vanished
between the two reads, the second GetInbound returned nil and
inbound.Remark panicked. The callback handler runs on a bare goroutine
with no recover(), so that panic killed the whole panel process.

Fetch the inbound once in a shared chooseInboundClient helper that
answers an error callback on a missing row, and pass the row down to
getInboundClientsFor instead of re-reading the DB, removing the
between-reads window. Route all three OnReceive handler paths through a
recover() barrier so no handler panic can take down the process, and log
the GetInbound failure instead of silently swallowing it.

internal/web/service/tgbot/tgbot_inbound.go

@@ -109,12 +109,7 @@ func (t *Tgbot) getInboundsFor(nextAction string) (*telego.InlineKeyboardMarkup,
 }
 
 // getInboundClientsFor lists clients of an inbound with a specific action prefix to be appended with email
-func (t *Tgbot) getInboundClientsFor(inboundID int, action string) (*telego.InlineKeyboardMarkup, error) {
-	inbound, err := t.inboundService.GetInbound(inboundID)
-	if err != nil {
-		logger.Warning("getInboundClientsFor run failed:", err)
-		return nil, errors.New(t.I18nBot("tgbot.answers.getInboundsFailed"))
-	}
+func (t *Tgbot) getInboundClientsFor(inbound *model.Inbound, action string) (*telego.InlineKeyboardMarkup, error) {
 	clients, err := t.inboundService.GetClients(inbound)
 	var buttons []telego.InlineKeyboardButton