Long-term: add Python parser to .NET tool and drop pythonnet dependency

[mircealungu]

The C# tool already has parsers for C#, Java, Go, and Kotlin. Adding a Python import parser to the .NET side would mean:

• No more pythonnet dependency
• No more DLL bundling in a pip package (MANIFEST.in graft .dotnet)
• Publish as a dotnet tool — clean, cross-platform, single binary
• The Python package becomes either legacy or a thin wrapper

Python imports are simpler to parse than C# using directives — the existing regex-based parser approach would work fine.

This would simplify packaging, installation, and CI significantly.