Washington Mayor Muriel Bowser has unveiled her last budget, a $21.2 billion gross operating spending plan that is sure to erupt into battles on the District Council and Capitol Hill, where Republican lawmakers have shown a growing willingness to interject themselves into local affairs. Bowser’s proposal, given to the Council Friday, makes education and health care spending priorities but would cut funding for several areas, including $127 million set asides for future collective bargaining agreements and non-union pay increases for city employees.