Fix: Cross-drive file crash (CLI-68)

[szmania]

Summary

This PR addresses the cross-drive file crash issue (CLI-68) where the application fails when handling files across different drives on Windows.

Changes

• Fixed file path handling for cross-drive operations on Windows
• Added proper drive letter normalization and path resolution
• Improved error handling for filesystem operations across drive boundaries

Testing

• Verified fix works with files on different drives (C: → D:, etc.)
• Tested edge cases: UNC paths, network drives, substituted drives
• All existing tests pass

Checklist

• Code compiles without errors
• All unit tests pass
• Integration tests pass
• Manual testing on Windows cross-drive scenarios completed
• No breaking changes to existing functionality

Related Issues

• Fixes CLI-68: Cross-drive file crash