refactor: change filter engine

[br-monteiro]

This pull request refactors and extends the filtering logic for the senior-stock command, introducing a new, more flexible filtering engine and updating the CLI interface and documentation to support a broader set of filter operations. The change also updates the tests to match the new syntax and behavior.

Filtering system overhaul:

• Introduced a new FilterEngine class in common/filter.py that supports multiple filter types (e.g., [eq], [re], [ne], [lt], [gt], [contains], etc.), allowing for much more expressive and powerful filtering on stock data. The filter logic is now centralized and easier to extend.
• Replaced the old inline filter parsing and logic in commands/senior-stock/__init__.py with the new FilterEngine, removing the parse_filters function and updating the command to use the new engine for all filtering. [1] [2] [3]

CLI and documentation updates:

• Updated CLI help texts for --filter, --columns, and --all-columns options to document the new filter syntax and available filter types, improving usability and discoverability.
• Updated the README documentation to show the new filter syntax (e.g., ean[eq]12345 instead of ean:12345). [1] [2]

Testing updates:

• Refactored and extended tests in tests/commands/senior-stock/test_command.py to cover the new filter syntax and additional filter types, ensuring correctness and backwards compatibility. [1] [2] [3] [4]