test: add case-aware path and diff CLI regression coverage

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Risky behavior now covered

• is_kotor_install_dir (diff CLI + TSLPatcher diff engine): installation detection with case-mismatched directory paths on POSIX (regression guard for case-aware application Case-aware application #151)
• ConfigReader.from_filepath: loading changes.ini when the on-disk filename casing differs from the requested path
• load_kits_unified: discovering kit JSON files when the kits root directory casing differs
• CaseAwarePath directory cache: clear_cache() allows resolution to track renamed directories after cache invalidation
• normalize_path_arg: PowerShell/Windows quote-mangling edge cases that previously had no direct tests

Test files added/updated

• Libraries/PyKotor/tests/common/test_case_aware_consumers.py (new)
• Libraries/PyKotor/tests/cli/test_diff_cli_utils.py (new)

Why these tests materially reduce regression risk

Case-aware path resolution was rolled out across core extract, diff, and patcher entry points. Without targeted tests, a future refactor to plain pathlib.Path could silently break Linux/macOS installs where users or tooling pass lower-case paths to mixed-case game directories. The normalize_path_arg tests protect diff CLI path parsing that handles real-world PowerShell quoting bugs.

Validation

cd Libraries/PyKotor
uv pip install pytest pytest-timeout loggerplus
PYTHONPATH="src:../Utility/src" uv run python -m pytest --import-mode=importlib --timeout=120 --noconftest \
  tests/common/test_case_aware_consumers.py tests/cli/test_diff_cli_utils.py -v

All 11 tests passed on Linux (POSIX case-resolution tests skip on Windows by design).

  

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🔨 Build Validation Summary

✅ Version Check: Passed

Tool Builds

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⚠️ HoloPazaak: cancelled
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🎉 All builds validated successfully! This PR is ready for merge.