docs(02-02): complete gnomAD evidence layer integration plan
- DuckDB persistence: gnomad_constraint table with CREATE OR REPLACE (idempotent)
- CLI evidence command: usher-pipeline evidence gnomad with checkpoint-restart
- Provenance tracking: records processing steps, saves sidecar JSON
- Query helpers: query_constrained_genes validates GCON-03 interpretation
- 12 integration tests: end-to-end pipeline, checkpoint, provenance, CLI
- Phase 2 complete: Evidence layer pattern established for future sources
- Duration: 4 min, 2 tasks, 5 files, 70 tests passing
Phase 2 (Prototype Evidence Layer) complete.