Release procedure

Replace x.y.z with the new version throughout. Steps 1-3 only edit files; make them on a release branch.

Steps

Update the version number in pyproject.toml and Cargo.toml (the two must match).
Update CHANGELOG.md:
- Promote [Unreleased] to a new [x.y.z] - YYYY-MM-DD section.
- Update the comparison links at the bottom.
Regenerate Cargo.lock:
```
cargo generate-lockfile
```
This bumps the phonors entry to x.y.z and may also refresh transitive dependencies to their latest compatible versions, so sanity-check that it still compiles before committing:
```
cargo check --release
```
(A plain cargo build fails to link locally because the pyo3 extension needs the Python interpreter symbols; the wheels are built with maturin in CI, not with bare cargo build.)

Commit on a release branch and open a PR:

git switch -c release/vx.y.z
git add pyproject.toml Cargo.toml Cargo.lock CHANGELOG.md
git commit -m "Release vx.y.z"
git push origin release/vx.y.z

Merge the PR once CI is green.

Tag the merged commit on main and push the tag:
```
git switch main && git pull
git tag vx.y.z
git push origin vx.y.z
```
Pushing a v* tag triggers the release workflow (.github/workflows/release.yml), which builds wheels and the sdist for all supported platforms.
Approve the PyPI upload. The publish-pypi job runs in the pypi GitHub environment, which has a required reviewer, so the run pauses at that job. Open the run in the Actions tab, click "Review deployments", and approve pypi. The wheels are built but never uploaded until this approval is given.
Verify the release: check the new version on https://pypi.org/project/phonors/ and pip install phonors in a fresh virtualenv.
conda-forge updates itself. A bot opens a PR against conda-forge/phonors-feedstock referencing the new PyPI sdist within a few hours; review and merge it (fix the recipe first if the dependencies changed).

A TestPyPI rehearsal is available before tagging: trigger the workflow manually (gh workflow run release.yml --ref main, or Actions -> Release -> "Run workflow"). workflow_dispatch publishes to TestPyPI; only a v* tag publishes to PyPI.