Use uv in CI instead of pip

Everywhere else in this repo (AGENTS.md, local dev commands) uses `uv run`,
and there's already a committed uv.lock -- CI was the odd one out, floating
dev-dependency versions on every run via `pip install --group dev` instead
of installing the exact locked versions. Switch to astral-sh/setup-uv +
`uv sync --group dev`, and run every subsequent command via `uv run` for
consistency and speed. build/twine aren't part of the dev dependency group,
so they use `uv run --with <tool>` for ephemeral installs rather than
adding packaging-only tools to the lockfile.

Verified locally: uv sync, ruff, mypy, pytest, build --sdist, twine check,
sphinx-build (html + doctest), and python -m doctest README.rst all pass.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: derek73

.github/workflows/python-package.yml

@@ -28,21 +28,21 @@ jobs:
       uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
+    - name: Install uv
+      uses: astral-sh/setup-uv@v6
+      with:
+        enable-cache: true
     - name: Install dependencies
-      run: |
-        python -m pip install --upgrade "pip>=24.2" setuptools
-        python -m pip install build
-        python -m pip install twine
-        python -m pip install --group dev
+      run: uv sync --group dev
     - name: Run linter
-      run: ruff check
+      run: uv run ruff check
     - name: Check types
-      run: mypy
+      run: uv run mypy
     - name: Run Tests
       run: |
-        pytest
-        python -m build --sdist
-        twine check dist/*
-        sphinx-build -b html docs dist/docs
-        sphinx-build -b doctest docs dist/doctest
-        python -m doctest README.rst
+        uv run pytest
+        uv run --with build python -m build --sdist
+        uv run --with twine twine check dist/*
+        uv run sphinx-build -b html docs dist/docs
+        uv run sphinx-build -b doctest docs dist/doctest
+        uv run python -m doctest README.rst