v1.6: 23-feature SV model as external-validation primary; seq-only caller-independent secondary

Add sequence-only headline model (svspr_v14_seq, 11-feature) + inference package

Model card: add sequence-only headline model (seqonly/)

Fix tier override to apply full config rules (SV 5-rule->LOW, STR 6-rule->WARNING); document HPRC 194-genome multi-sample validation

SVSTR-Score v13 models, locus lookup, inference, model card, real cohort examples

initial commit