[prrao87]

Why

The Python suite runs one test at a time, so a 4-core CI runner and a multi-core laptop both sit mostly idle during make test. Running the tests across worker processes makes the local loop and the Python Tests CI job faster without changing any test.

What changed

• pytest-xdist joins the dev dependency group, so make install brings it in.
• make test and the Python Tests workflow run pytest with -n auto, one worker per core. PYTEST_ARGS="-n 0" still runs the suite serially when debugging a single test, since the later -n wins.
• The release workflow's wheel tests are unchanged. Each takes about 30 seconds and already runs as a parallel matrix.
• Nothing changes for users of the package: no API, behaviour or documentation changes.

Validation

Local timings on an Apple Silicon laptop with the debug build, the same 1645 tests passing in each run:

Run	Wall time
Serial (before)	25.4s
-n 4 (the CI runner's core count)	10.8s
-n auto	8.1s

• uv lock --check passes; the lockfile adds only pytest-xdist and execnet.
• uvx typos@1.26.0 . passes.
• No benchmark runs, since the change touches only test tooling and no lance-csr code.
• The timings above come from a local build, not from this branch's own build. The Python Tests run on this PR is the check on this branch; its pytest step took 63s serially on main, and I expect it to drop to about 25s.

🤖 Generated with Claude Code

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