BOGOTA, Colombia — Sitting in the living room of a friend’s home, with bodyguards hovering outside and a bust of Lenin standing in the corner, Aida Avella knows she’s testing a concept: Can an openly leftist politician safely run for office in this polarized country? The answer to that question could be the difference between war and peace, as Colombia tries to end a half-century conflict with Latin America’s largest guerrilla group. Avella is the president of the ill-fated Union Patriotica party, and she’s running to recapture the Bogota City Council seat she had to abandon in 1996 after assailants attacked her caravan with a rocket launcher and automatic weapons.