It doesn’t have the gritty look you’d expect of a 20-year-old jail that has housed thousands of accused murderers, robbers, gang members and immigrants detained by federal authorities. Two-person dorm-style cells remain clean and tidy, with dark blue tables, mint green bunk beds and doors with glass windows rather than cage-like metal bars. There is clean, blue and beige carpet to muffle ambient noise and large areas where inmates can mingle, watch TV, play board games or…