New Features:
- Add `Priority` enum and `priority` field to `Card` model.
- Add `TicketComment` model and `TicketCommentCreateView` with inline comment support.
- Introduce templatetag filters `add_class`, `field_type`, and `render_markdown`.
Enhancements:
- Extend `CustomUser.is_admin()` to recognise superusers.
- Populate `KanbanConfig.ready()` to import signals for proper initialization.
- Expand ticket views and URLs to include assignee, priority, and comment handling.
Bug Fixes:
- None.