fix(clients): derive edit-form flow from per-inbound override

SyncInbound runs once per inbound and unconditionally overwrites the canonical clients.Flow column. A non-flow inbound (Hysteria, WS, gRPC) strips flow to "", so when it syncs after a VLESS Reality inbound the column is wiped, and the hydrate endpoint returned that empty value — the edit form loaded a blank flow for multi-inbound clients (#4792).

Derive the hydrate flow from the first flow-capable client_inbounds.flow_override instead, which is always correct and order-independent. A non-empty guard in SyncInbound was rejected because it would make flow impossible to clear.

Closes #4792

web/controller/client.go

@@ -93,6 +93,12 @@ func (a *ClientController) get(c *gin.Context) {
 		jsonMsg(c, I18nWeb(c, "get"), err)
 		return
 	}
+	flow, err := a.clientService.EffectiveFlow(nil, rec.Id)
+	if err != nil {
+		jsonMsg(c, I18nWeb(c, "get"), err)
+		return
+	}
+	rec.Flow = flow
 	jsonObj(c, gin.H{"client": rec, "inboundIds": inboundIds}, nil)
 }