Modernize packaging + CI: setup.cfg -> pyproject.toml, legacy workflow -> uv-CI stub (and fix the red CI)

[thorwhalen]

Modernizes udos from legacy packaging (setup.cfg + setup.py + the 2022-era
inline CI workflow) to the current ecosystem standard: pyproject.toml with
Hatchling, plus the 5-line wads uv-CI stub that reads everything from
[tool.wads.ci.*].

It also fixes the long-standing red CI on master — the cause turned out to be a
real one, not an artifact of the old workflow. Details below.

⚠️ Merging this PR publishes a release to PyPI. [tool.wads.ci.publish] is
enabled (fleet default), and this package is already on PyPI at 0.0.2.
[project].version is deliberately set to 0.0.2 so CI's automatic bump lands
on 0.0.3 rather than re-publishing behind the released version. See
"Decision for the maintainer" at the bottom before merging.

What changed

Commit	What
packaging:	setup.cfg/setup.py → pyproject.toml (Hatchling); legacy files deleted
ci:	legacy inline workflow → uv-ci.yml@master stub
tests:	one import smoke test + the missing .editorconfig
style:	ruff format . (the formatter the new CI runs)

Inventory carried across from setup.cfg

Everything in the old [metadata]/[options] was accounted for:

setup.cfg	pyproject.toml
name = udos	[project].name
version = 0.0.2	[project].version (kept at the released version — see above)
description	[project].description
long_description = file:README.md, long_description_content_type = text/markdown	[project].readme = "README.md"
url	[project.urls].Homepage
license = apache-2.0	[project].license = "Apache-2.0" (SPDX string, not the deprecated [project.license] table); LICENSE kept and now shipped in the wheel's dist-info/licenses/
packages = find:	[tool.hatch.build.targets.wheel].packages = ["udos"]
install_requires (empty)	dependencies = []
keywords (empty)	filled in with real keywords

Deliberately dropped, each with a reason:

• platforms = any, zip_safe = False — setuptools-only knobs with no effect on
  wheel builds.
• include_package_data = True — Hatchling ships everything under the package
  directory by default; udos/ has no data files anyway.
• root_url — read only by populate at project-creation time to derive the
  project URL, which is now written out explicitly.
• display_name = udos — identical to the project name, which is epythet's
  default when [tool.epythet].display_name is absent, so nothing is lost.

There were no entry_points / console scripts, no package_data, no extras
and no python_requires in the old config, so nothing of that kind could be
dropped. MANIFEST.in and requirements.txt do not exist in this repo.

Added while here (the [project] block was otherwise bare on PyPI): authors,
keywords, classifiers, requires-python = ">=3.10", and
Repository/Documentation URLs. Also the standard [tool.ruff] block, without
which the repo would drift onto ruff's moving defaults and go red on unrelated
style changes.

Latent bug this surfaced: the red CI was real

The last run on master (actions/runs/17236567336) failed on Validation (3.10), and it would have kept failing after the migration.

udos is a placeholder package: udos/__init__.py contains a module docstring
and nothing else. Both the old workflow (pytest --doctest-modules -v udos) and
the new one (pytest --doctest-modules, collection driven entirely by
testpaths) therefore collect zero items, and pytest exits with code 5
("no tests collected"). run-tests-uv runs under set -e, so a non-zero exit is
a red build.

Two ways to fix it:

1. [tool.wads.ci.testing].enabled = false — the sanctioned wads knob for repos
   with no suite.
2. Give the repo one real, minimal test.

(2) is what this PR does, in tests/test_smoke.py. Option (1) would switch
the test step off permanently, so the day udos grows actual modules their
doctests would silently not run — exactly the failure mode that testpaths
hygiene exists to prevent. No repo in the ecosystem currently disables testing,
and an empty placeholder is a poor place to set that precedent.

Relatedly, testpaths is set to ["udos", "tests"] rather than the migration
tool's unconditional ["tests"], so package doctests are collected the moment
there are any.

No package behaviour was changed to make CI pass.

Docs build still works after deleting setup.cfg

docsrc/conf.py passes setup.cfg to epythet.config_parser.parse_config.
That function falls back to pyproject.toml when the file is missing, so the
Pages job is unaffected. Verified locally — it now resolves to
('udos', '', 'Thor Whalen', '0.0.2', 'udos'), i.e. the same project and display
name as before, plus an author it previously had no way to find.

Verification

• Local gate (priv test-dependents udos, mirrors CI):
  baseline no-tests (0 pass / 0 fail) → final pass (1 pass / 0 fail).
  udos has no local dependents.
• Wheel build: uv build succeeds; metadata inspected — SPDX
  License-Expression: Apache-2.0, License-File: LICENSE, all classifiers,
  URLs and keywords present, README rendered as the long description.
• Dependencies: cross-checked with wads-deps. It flags only setuptools
  (from setup.py, now deleted) and epythet (from docsrc/conf.py, a docs
  tool). Neither is a runtime import, so dependencies stays empty — correct
  for a module that imports nothing.
• Branch CI: https://github.com/i2mint/udos/actions/runs/30859403663 —
  success. Read Configuration ✓, Validation (3.10) ✓, Validation (3.12) ✓,
  Windows Tests ✓; Publish and Publish GitHub Pages skipped as expected on a
  non-default branch.
• Repo audit (python -m wads.repo_audit): HIGH 2 / MEDIUM 3 / LOW 3 →
  HIGH 1 / MEDIUM 0 / LOW 3. Cleared: no-pyproject, legacy packaging files,
  legacy CI generation, no test files, missing .editorconfig. The remaining
  HIGH is the historical failed run on master, which clears when this merges.

Left undone on purpose

• GitHub repo metadata — the homepage field is empty and topics are unset;
  the audit wants https://i2mint.github.io/udos/ and the slugified keywords.
  These are repo settings, not files, so they cannot ship in a PR, and the
  command was not run in this session. To align:
  gh repo edit i2mint/udos --homepage "https://i2mint.github.io/udos/" plus
  --add-topic for dataset data standard search acquisition sharing.
• Agent skills (wads-skillify) — out of scope for a packaging pass, and
  premature for a package with no API yet.
• A real test suite / docs — there is no behaviour to test or document yet.
  The smoke test exists solely so the CI test step stays enabled and meaningful.

Decision for the maintainer

udos has been a docstring-only placeholder since 2022 and has one PyPI release
(0.0.2). Merging republishes it as 0.0.3 — an empty package. That is harmless
(it holds the name), but if you would rather not spend a release on it, set
[tool.wads.ci.publish].enabled = false before merging and flip it back when the
package actually has content. Tracked in #1.