Fix v1.1.0 charset_normalizer packaging regression

[mspinolaeie]

Summary

• fix the PyInstaller release packaging regression introduced by the markitdown 0.1.5 bump
• explicitly include charset_normalizer and its md__mypyc runtime in the frozen app
• add packaging regression tests by moving the spec collection logic into a testable helper module

Testing

• pytest -q tests\test_build_config.py tests\core\test_conversion.py tests\ui\test_home_state.py tests\utils\test_update_checker.py tests\utils\test_translations.py tests\core\test_settings.py tests\core\test_file_utils.py
• pyinstaller --clean --noconfirm --log-level WARN MarkItDown.spec smoke build, then verify dist/MarkItDown/_internal/charset_normalizer contains both md*.pyd and md__mypyc*.pyd

Closes #23

[imadreamerboy]

Looks good, thank you!