1) Userless orders will be merged on user's registration by their phone number and/or email. Added Viewset action "merge_recently_viewed" so recently viewed products may be stored on server's side.
2) Added comprehensive products' filtering by category(support for including subcategories)
Fixes: I18N
Fixes: 1) Removed redundant import for `ValidationError` from `rest_framework.exceptions`; 2) Fixed request data handling in `confirm_password_reset` to directly use incoming data instead of serialized data;
Extra: 1) Minor adjustments to error messages for consistency; 2) Cleaned up unused variables in `confirm_password_reset`.
Fixes: 1) Resolve inconsistent variable usage in `confirm_password_reset` by replacing `data` with `serializer_data` across the method;
Extra: 1) Minor cleanup for improved clarity and maintainability.
Fixes: 1) Correct mismanagement of instance and serializer in update method of viewset.
Extra: 1) Minor organizational improvement and clearer formatting in views.
Fixes: 1) Adjust password reset serializer to use `request.data` instead of `self.request.data`; 2) Remove unnecessary language scoping from category query.
Extra: None;
Fixes: 1) Adjust import order in `core/models.py` for better consistency;
Extra: Refactor formatting for better readability in `core/models.py`; Update `pyproject.toml` version to 2.6.2; Update compiled translation file `cs_CZ/LC_MESSAGES/django.mo`.
