Ruff: declare adapter re-exports via __all__ in docling_extractor
(F401) and sort the engine import block in the adapter test (I001).
Pytest: engine-dependent tests now importorskip the pinned engine —
CI installs light deps only and the engine repo is private, so they
skip visibly there and run in Docker/dev envs with the engine.
Verified: ruff clean; pytest 74 passed + 2 skipped without engine,
80 passed with the pinned engine v0.1.0 installed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
