Fix CI: replace Autotools template with Python/uv workflow steps

[Copilot]

The Makefile CI workflow was generated from GitHub's C/C++ Autotools template, causing an immediate failure because ./configure, make check, and make distcheck don't exist in this Python/uv project.

Changes

• .github/workflows/makefile.yml: Replace Autotools commands with the correct steps for this project:
  • Add actions/setup-python@v5 (reads Python version from .python-version)
  • Add astral-sh/setup-uv@v6 to install the uv package manager
  • make install → uv sync
  • make build → uv build
  • make test → uv run pytest -q

# Before (broken)
- name: configure
  run: ./configure        # No such file — not an Autotools project
- run: make check
- run: make distcheck

# After
- uses: actions/setup-python@v5
  with:
    python-version-file: .python-version
- uses: astral-sh/setup-uv@v6
- run: make install
- run: make build
- run: make test