fix(inbounds): preserve client data on delete and show traffic in detail

Deleting an inbound now only detaches its clients (removes the
client_inbounds rows). It no longer deletes client_traffics or client IP
logs: those are keyed centrally by email (one row per client) and must
survive, since a client may stay attached to other inbounds and is
managed from the Clients page.

Separately, /get/:id now uses a new GetInboundDetail that preloads and
enriches ClientStats, so hydrated records (info / QR / export) carry
per-client traffic instead of null. DBInbound.toJSON drops the internal
_clientStatsMap cache so it no longer leaks into the exported JSON.

web/controller/inbound.go

@@ -121,7 +121,7 @@ func (a *InboundController) getInbound(c *gin.Context) {
 		jsonMsg(c, I18nWeb(c, "get"), err)
 		return
 	}
-	inbound, err := a.inboundService.GetInbound(id)
+	inbound, err := a.inboundService.GetInboundDetail(id)
 	if err != nil {
 		jsonMsg(c, I18nWeb(c, "pages.inbounds.toasts.obtain"), err)
 		return