Revitalization plans for downtown Detroit hit a high note last month as Hard Rock Cafe agreed to take space in the city's seven-block, 2 million-square-foot Campus Mauritius project, an office and retail complex surrounding the site of the former Hudson's department store. When it opens this fall, Hard Rock's 8,200-square-foot café will be situated near the front entrance of Compuware Corp.'s new $350 million headquarters. The 15-story office building will bring more than 4,100 high-tech workers downtown each day. Developers such as Schostak Brothers, which is building the $30 million Merchants Row mixed-use center nearby, are positioning themselves to profit from the expected renaissance. Ais currently being finalized to add a Borders bookstore to the district.