Mixed Python + non-Python projects not properly supported

[mircealungu]

From review of PR #81.

If a user configures fileExtensions: [".py", ".cs"] (or any mix including .py), the should_run_dotnet logic sends everything to the C# dotnet path:

def should_run_dotnet(config):
    return "fileExtensions" in config and ((len(config["fileExtensions"]) > 1) or (".py" not in config["fileExtensions"]))

Since len > 1, the dotnet path runs — but the C# parsers don't handle .py files, so Python dependencies are silently lost.

The Python parser (astroid) also can't handle .cs/.java/.go/.kt, so there's no single path that works for mixed projects today.

Questions to discuss

• Should mixed projects be explicitly disallowed in the config schema for now?
• Or should the tool run both parsers and merge the graphs?
• Should the config schema validation reject combinations that include .py alongside other extensions?