restore the ability to run individual files

As I link everything to the entrypoint, it's getting harder to run individual files-- I'm not sure if this is good (should have a single point of truth to call into) or bad (it's a little annoying if you just want to run or test one thing). We could fix this by re-writing an entrypoint method into each file

Look at the project's entrypoint and how it currently links modules. The goal is to modify the build or import system so individual files can be executed directly, perhaps by adding a `__main__` guard or a script wrapper. Check existing Python files for import patterns and see if there's a setup.py or similar configuration. 'Done' means you can run a single file from the command line without going through the main entrypoint.

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