CREATE TABLE IF NOT EXISTS notifications (
  id INT AUTO_INCREMENT PRIMARY KEY,
  user_id INT NOT NULL,
  title VARCHAR(150) NOT NULL,
  body VARCHAR(500) NULL,
  link VARCHAR(255) NULL,
  is_read BOOLEAN NOT NULL DEFAULT FALSE,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
  INDEX idx_user_time (user_id, created_at)
);