Protesters gathered at a sports stadium Sunday as Hong Kong braced for more anti-government rallies, a day after clashes returned to the city’s streets following several days of relative calm. Hong Kong has been gripped by three months of street demonstrations that started against a proposed extradition bill to China, but have spun out into a wider pro-democracy movement. The MTR — the city’s metro — is the latest Hong Kong business to be rebuked by the public, after appearing to bend to Chinese state-media attacks accusing the transport system of being an “exclusive” service to ferry protesters to rallies.