Temu has grown into an ecommerce giant in a very short time. Photo: ShutterstockForget Amazon, eBay, and Alibaba: last year’s fastest-growing shopping site was Chinese company Temu – yet even as its dizzying success shaped Australia’s holiday shopping season, complaints, security concerns, and legal battles have cast shadows over its long-term future.That future seemed bright last April, when Temu added Australia and New Zealand to its fast-growing business in Canada and the United States – where its bargain prices and massive inventory of fashion, clothing, technology, homewares and myriad other products drove user numbers to stratospheric heights.From just 440,000 downloads when…