[mmacferrin]

Description

Adds an empty src/transformez/py.typed file. Under PEP 561, type checkers such as mypy only read an installed package's annotations when it carries this marker. Without it, they treat everything imported from transformez as Any, and downstream projects have to list transformez under ignore_missing_imports in their mypy settings. With it, calls into transformez are checked against its annotations in the calling project's type check.

This came out of a review of IVERT's CI (continuous-dems/ivert#220), which suggested marking fetchez, transformez and globato as typed, but only where the package itself is type-checked. transformez is: the "Type check" workflow runs mypy on every pull request.

The wheel and sdist pick up the file without any configuration change, since hatch includes everything under src/transformez; I checked that a built wheel contains it. IVERT, which imports transformez, has no new type errors with the marker in place.

fetchez is getting the same marker in continuous-dems/fetchez#501. Once that is released, this repository's "Type check" workflow, which installs the newest fetchez, will check how transformez calls it. Against that branch it found 16 errors. Half come from fetchez annotations that #501 tightens; this PR fixes the other 8, none of which change behavior:

• reference/fetcher.py gives the downloaded file names their own loop variable, rather than reassigning the loop's str variable to a Path (7 errors).
• api.plot_grid() is annotated to take a region string or list as well as a Region, as its docstring and code already do; transformez build --preview passes it a string (1 error).

With both PRs in, the type check is clean. This PR should be merged before the fetchez release that carries #501, or the "Type check" workflow will fail on every PR here until it is.

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Checklist

• PR title is descriptive
• PR body contains links to related and resolved issues (e.g. closes #1)
• If needed, CHANGELOG.md updated
• If needed, docs and/or README.md updated n/a
• If needed, unit tests added n/a
• All checks passing
• At least one approval

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🔍 Docs preview: https://transformez--200.org.readthedocs.build/en/200/