Keep the diatom signaling graph distinct from workflow and environmental prevalence #1741

CommunityMech:000056; PMID26017307. Remove consortium-resolution workflow and broad coastal-prevalence nodes from the exact-pair interaction graph; environmental prevalence already remains in environmental_factors. Preserve the three biological signal/exchange nodes and the existing IAA-to-cell-division arrow. Remove categorical MUTUALISM labels from individual processes, retain reported precursor use, signaling and nutrient exchange without claiming complete flux balance or independently verified reciprocal fitness from the accessible abstract. Use canonical participants on the collective node and retain prior workflow-arrow removals. No new growth mechanisms, toxin guidance, cultivation optimization or experimental designs. Close only after protected-main merge.

Dedup:1006 all-state issue titles/bodies searched by IDs, PMIDs, names and broad substrate/taxon aliases. All nine matching bodies read; none is this graph repair. Explicitly read529/573/605 for general source/panel/membership scope.49 local matching files found with ignored/hidden included; .git/docs/site/references_cache excluded, relevant caches separately inspected. Comments and PRs not exhaustive. Self-adversarial review, not independent approval.