Fixes: 1) Addressed missing or incorrect imports and type hints with `# ty:ignore` markers; 2) Fixed search queryset error handling in filters module; 3) Resolved issues in viewsets with updated `@action` method usage.
Extra: Removed unused classes and dependencies (e.g., `BaseMutation`, `basedpyright`, and related packages); streamlined GraphQL mutation implementations; cleaned up unused arguments in model `save` methods.
Fixes: 1) Ensure safe next URL handling with host validation;
Extra: 1) Introduce new i18n module with language normalization and translation support; 2) Add route for language setting endpoint.
Fixes: 1) Correct line references in locale files for consistency;
Extra: Improve formatting and alignment of string segments for clarity and maintainability;
