- Add birth_date, created_at/updated_at to Employee; remove username field
- Introduce EmployeeAction for tracking HR events and is_actually_active/status properties
- Create BotSubscriber model (OneToOne relation) for TG/WA binding
- Implement Aiogram-based Telegram bot:
• request contact to bind by phone or @username
• department selection keyboard from DEPARTMENTS dict
• async ORM via sync_to_async, custom filters for bound & active employees
- Update profile view & template:
• show “Bind Telegram/WhatsApp” button only when not already bound
• preview avatar on upload
- Remove registration tokens in favor of contact-based auth
- Clean up templates, forms and add avatar validation mixin
