build!: use uv_build, static versioning, and Python >=3.11

[tobiasraabe]

Changes

Generated plugins now use uv_build and declare a static initial version of 0.1.0 in pyproject.toml. Builds no longer need Git metadata or setuptools-scm, and the package's version reads the installed distribution metadata. Remove the SCM configuration, generated-version-file ignores, MANIFEST.in, and setuptools-specific settings. Keep the src layout and include the generated changelog in source distributions.

Move generated-plugin project metadata and the pytask entry point into pyproject.toml, remove both setup.cfg files and their formatting hooks, and provide the missing plugin.py hook module. Use SPDX license identifiers with explicit license-file inclusion, including the Not open source option; fix the ISC license-template branch to match the offered choice. Generated URLs use the configured GitHub owner and the actual CHANGES.md file.

The template and generated plugins require Python 3.11 or newer. Generation validation, CI matrices, and the default interpreter selection are updated accordingly, and the existing template lockfile is regenerated. Changelog entries link this PR.

Validation

• On Python 3.11, just lint and just typing passed; all six end-to-end tests passed.
• Generated source distributions and wheels built for all six license choices from copies without Git metadata, with version 0.1.0 and Requires-Python >=3.11.
• Installed-wheel tests passed for MIT and Not open source, verifying static version metadata, pytask entry-point loading, and CLI discovery without Git metadata or SCM version overrides.
• The template source distribution and wheel built successfully.