VANCOUVER, British Columbia — Every day when he arrives at his office in City Hall, Mayor Ken Sim stares at a prominent black-and-white photograph of Chinese railway workers toiling on the tracks in British Columbia in 1884. Mr. Sim, the son of Hong Kong immigrants, said the workers’ weathered faces are a daily reminder of the symbolic importance of his election as Vancouver’s first Chinese Canadian mayor, and of just how far Chinese Canadians have come. Six months ago, his historic landslide victory was widely lauded, viewed as the triumph…