The yen briefly surged to the mid-142 level against the U.S. dollar in Tokyo trading on expectations of a Bank of Japan policy shift, with a cautious tone also prevailing ahead of U.S. employment data due out later in the day. The firm yen sent Tokyo stocks sharply lower on concerns exporters could see their profits squeezed by their stronger home currency. At 3 p.m., the dollar fetched 143.92-97 yen compared with 144.13-23 yen in New York and 145.67-69 yen in Tokyo at 5 p.m. Thursday. The euro was quoted at $1.0783-1.0784 and 155.19-26 yen against $1.0788-0798 and 155.51-61 yen in New York an…