feat: prepare climate-api for PyPI release

[turban]

Closes #62.

What

Prepares climate-api for PyPI publication.

Changes

Flat package layout

src/climate_api/ moved to climate_api/ at the project root. Updated pyproject.toml ([tool.uv.build-backend] module-root = ""), Makefile, and Dockerfile accordingly. No import paths change.

Blocker removed: dhis2eo git-sourced dependency

dhis2eo is removed from dependencies (it was already on PyPI as of PR #74). It is called lazily via importlib.import_module inside _get_dynamic_function, so the core API is unaffected. A ModuleNotFoundError handler now surfaces a clear install instruction if a download is attempted without the package.

Version bump: 0.1.0 → 0.1.0a1

PEP 440 alpha pre-release — invisible to pip install climate-api by default, opt-in via pip install --pre climate-api or an explicit pin.

Package metadata

Added to pyproject.toml: license, authors, readme, keywords, classifiers, [project.urls]. A LICENSE file is included at the project root.

Publish workflow

.github/workflows/publish.yml — triggers on v* tags, builds with uv build, publishes via Trusted Publishing (no API token stored in secrets).

What still needs doing before first publish

1. Register climate-api on PyPI and configure Trusted Publishing for this repo
2. Create a pypi environment in repo settings
3. Push a v0.1.0a1 tag

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Restores PR #75, which was accidentally merged then reverted.