vdjtools 5.2.2

Requires seqtree >=1.3.1,<2, ensuring the released input-length gap-prior preparation fix is available.

Algorithms, native scoring kernels, ingestion behavior and bundled recombination models are unchanged from 5.2.1. The native/Python version advances consistently to 5.2.2.

Integration: #205. Release promotion: #206. Cross-platform CI includes the complete Linux reference/EM suite, plus native/dependency smoke and strict documentation checks.