If you’ve ever been inside Twin Oaks estate, that massive mansion in Cleveland Park on Woodley Avenue NW between Wisconsin and Connecticut avenues, you are in rare company: it’s the largest privately owned estate in D.C. that doesn’t house the president, and it’s only open to the public for special events. The Taipei Economic and Cultural Representative Office (TECRO) runs Twin Oaks now, using it to host Taiwanese diplomatic and cultural events. This year, TECRO…