MOSCOW — After four days of peace and music in a meadow outside Moscow, an unlikely assortment of Russians pulled up the stakes on their tents and went home, looking as if they had just shared a Woodstock moment. Instead of organizing another human rights or environmental protest — which are rarely permitted and widely considered futile by the public — activists decamped to the Khimki Forest on Friday for entertainment and enlightenment, with music, lectures and debates lasting until Monday afternoon.