Fixes: 1) Remove unused import of `AbstractGateway` from `payments/signals.py`; 2) Adjust type hints in `AbstractGateway` methods to use `Any` instead of `Transaction`;
Extra: 1) Replace unused import of `Transaction` in `payments/gateways/__init__.py` with `Any`.
Fixes: 1) Correct line references in locale files for consistency;
Extra: Improve formatting and alignment of string segments for clarity and maintainability;