-- Migration: Add user notification settings
-- Date: 2025-01-XX
-- Description: Adds notification_settings column to users table for storing notification preferences in JSON format

-- ===== Add notification_settings column to users table =====
-- Add JSON column to store notification settings
ALTER TABLE users 
ADD COLUMN notification_settings JSON DEFAULT NULL COMMENT '通知設定（JSON形式）';

-- Note: JSON format example:
-- {
--   "method": "slack" | "email",
--   "slack_webhook_url": "https://hooks.slack.com/services/..." (only when method is "slack")
-- }

