BARNSTABLE — The scene at Barnstable High School on a recent Monday night felt like a homecoming rally — all anxious energy, cheers, and hugs. A crush of bodies flooded the hallway as revelers greeted friends and handed out fliers to people pouring into the auditorium. Except these weren’t high schoolers filling the corridor. This was a public meeting for Barnstable residents to discuss a developer’s plans to lay transmission cables from offshore wind projects under their beaches. For the most part, these residents were opposed, and they were demanding to be heard.