feat: adopt the copick 2 alpha runtime

[uermel]

Tracks #33 and #34 and is the first PR in the copick-easymode OME-Zarr 0.5 / Zarr v3 migration stack.

This establishes the nonzero test and package gate while aligning the only resolvable runtime contract:

• Python 3.11-3.13 and copick>=2.0.0a1,<3;
• TensorFlow 2.20+ / NumPy 2 with a committed universal uv lock;
• an internal adapter for the immutable easymode source commit;
• offline CLI, option, model-list, and numerical baseline tests;
• reusable locked CI, artifact inspection, and installed-wheel help smoke; and
• exact tagged-easymode compatibility validation without model downloads.

The former Python 3.9 metadata could not resolve the existing copick dependency, so the planned runtime alignment is included with the initial gate rather than committing an unsatisfiable lock.

Validation: 15 tests pass on the first stack layer; Black/Ruff/pre-commit and action-validator pass; wheel and sdist inspection pass.

No release version, Release-As footer, PyPI publisher, or publication action is included.