Bound Fe2+ nitrate-removal graph to treatment endpoints and abundance evidence #1733

CommunityMech:000372; PMID:42520901. Preserve the single-node graph, measured nitrate-N removal improvement, and reported sequence-abundance shifts. Complementary named capacities do not demonstrate NICHE_PARTITIONING. Remove that categorical type and name all three canonical participants. The source calls its analysis metagenomic while reporting transcript abundance; retain this measurement ambiguity explicitly rather than treating it as verified transcription, ferredoxin production or pathway flux. Nitrate removal alone does not establish whole-system nitrogen loss. Add the existing abstract-backed performance evidence to the node. No new arrows or actionable protocols. Close only after protected-main merge.

All-state issue titles/bodies searched using references, IDs, full/short names and distinctive strain terms. Ignored/hidden local files included; .git/docs/site/references_cache excluded, relevant caches separately inspected. #353 is an unrelated numeric-ID match. Explicitly read closed #529 (general cultivation-source scope) and #878 (Klebsiella GTDB grounding); neither resolves this finding. Comments and PRs not exhaustively searched. Source-based self-adversarial review, not independent approval.