- Add TypeScript type exports for Activity, NewActivity, Reminder, NewReminder
- Create lead-validators.ts: Zod schemas for CRUD operations with Italian localization
- Create lead-service.ts: Query layer with 14 functions (leads, activities, reminders)
- Implement immutable activity audit trail with auto-update of lead.last_contact_date
- Add pipeline stage enums (6 stages) and activity type enums (4 types)
- Cascade delete configured for data integrity
- Full TypeScript type safety throughout
- npm run build: PASSED (0 errors)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>