TEHRAN — Protests spread across Bahrain over the weekend as demonstrators demanded the release of detained Shia scholars and clerics, and security forces responded by arresting at least 25 people in raids and summonses. Marchers filled streets in Sitra Island, Al-Hamala, Al-Markh and Iskan Ali, carrying portraits of jailed clerics and of Sheikh Isa Ahmed Qassim, the country’s senior Shia authority. Organizers called it a “Day of Popular Anger.