FOLLOW-UP AUTOMATION MODULE (B4)

Includes:
- Auto next follow-up date calculation
- Auto customer status update
- Reminder cron
- Automation logs table

Auto Rules:
- new lead / first call → +1 day
- followup call → +2 days
- site visit → +3 days
- proposal shared → +5 days
- negotiation → +7 days
- closed → no further follow-up

Cron:
php cron/followup_reminder.php (schedule daily every morning)

Migration:
mysql -u root -p dbname < sql/migrations/20251210_create_sd_followup_automation_logs.sql
