Migrate to uv, setuptools-scm, prek, and ruff

[rtibbles]

Summary

Migrate Kolibri's Python tooling from pip/tox/setup.py to uv, and replace flake8+black with ruff.

• Dev environments use uv sync --group dev for venv creation, Python version management, and dependency installation
• Versioning handled by setuptools-scm (replaces custom kolibri/utils/version.py generation logic)
• CI test workflows use uv for Python 3.8+; EOL Python (3.6, 3.7) remains on Docker containers with pip
• Build pipeline (make staticdeps) stays on pip — uv cannot resolve for Python 3.6
• Pre-commit replaced with prek; flake8, black, reorder-python-imports replaced with ruff

References

• Migrate morango to uv for package management morango#296
• Include uv.lock in path match check, to ensure we're not breaking CI morango#303

Reviewer guidance

Local verification before PR:

• make staticdeps tested in a Python 3.6 container — installs correctly
• uv build produces wheel and tarball
• Full test suite passes on Python 3.6 via PYTHONPATH
• Version utility tests (74) pass on 3.8+ via uv

For review:

• The ruff reformatting commit touches 439 files — review the config commits individually, not the reformat
• CI is the main verification — check that all workflow jobs pass across the Python version matrix
• Tests are not yet run against a built whl file — that's a deliberate follow-up

AI usage

This PR was authored collaboratively with Claude Code. Claude implemented the migration based on a brainstormed design, with each decision reviewed and approved interactively. Tests and build were verified in Python 3.6 containers.

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