refactor(py): clean up top-level genkit python organization

[huangjeff5]

While auditing the code base I found more unused stuff in the python repo. Continuing my cleanup. Removes the following:

• py/tools/schema_to_typing/schema_to_typing.py -> py/bin/schema_to_typing.py
• Deletes py/tools/ entirely (the only other content was an orphan PNG and a .DS_Store)
• Updates py/bin/generate_schema_typing to point at the new location
• drop dead test-runner shims (noxfile.py, tox.ini)
• drop typos config
• deleted model_performance_report.md (one-off file)
• remove poethepoet dev dep (not used)

[gemini-code-assist]

Code Review

This pull request removes the typos spell checker, nox, and tox configurations, and relocates the schema_to_typing.py script to the bin directory. Feedback points out that the header documentation in check_consistency needs updating to match the new check count and suggests including the relocated generator script in the linting process.